diff --git a/lib/relation-definition.js b/lib/relation-definition.js
index 2db36355..92c23ab2 100644
--- a/lib/relation-definition.js
+++ b/lib/relation-definition.js
@@ -101,8 +101,9 @@ RelationDefinition.prototype.toJSON = function () {
  */
 RelationDefinition.prototype.applyScope = function(modelInstance, filter) {
   filter.where = filter.where || {};
-  if (this.type !== 'belongsTo' && typeof this.typeTo === 'string') {
-    filter.where[this.typeTo] = this.modelFrom.modelName; // polymorphic
+  if ((this.type !== 'belongsTo' || this.type === 'hasOne')
+    && typeof this.typeTo === 'string') { // polymorphic
+    filter.where[this.typeTo] = this.modelFrom.modelName;
   }
   if (typeof this.scope === 'function') {
     var scope = this.scope.call(this, modelInstance, filter);
@@ -131,8 +132,9 @@ RelationDefinition.prototype.applyProperties = function(modelInstance, target) {
       target[key] = modelInstance[k];
     }
   }
-  if (this.type !== 'belongsTo' && typeof this.typeTo === 'string') {
-    target[this.typeTo] = this.modelFrom.modelName; // polymorphic
+  if ((this.type !== 'belongsTo' || this.type === 'hasOne')
+    && typeof this.typeTo === 'string') { // polymorphic
+    target[this.typeTo] = this.modelFrom.modelName;
   }
 };
 
@@ -365,10 +367,10 @@ RelationDefinition.hasMany = function hasMany(modelFrom, modelTo, params) {
   var fk = params.foreignKey || i8n.camelize(thisClassName + '_id', true);
 
   var idName = modelFrom.dataSource.idName(modelFrom.modelName) || 'id';
-  var polymorphic, typeTo;
+  var typeTo;
   
   if (typeof params.polymorphic === 'string') {
-    polymorphic = params.polymorphic;
+    var polymorphic = params.polymorphic;
     fk = i8n.camelize(polymorphic + '_id', true);
     typeTo = i8n.camelize(polymorphic + '_type', true);
     if (!params.through) {
@@ -1049,15 +1051,17 @@ RelationDefinition.hasAndBelongsToMany = function hasAndBelongsToMany(modelFrom,
     if (params.model) {
       modelTo = params.model;
     } else {
-      modelTo = lookupModel(models, i8n.singularize(modelTo)) ||
-        modelTo;
+      modelTo = lookupModel(models, i8n.singularize(modelTo)) || modelTo;
     }
     if (typeof modelTo === 'string') {
       throw new Error('Could not find "' + modelTo + '" relation for ' + modelFrom.modelName);
     }
   }
 
+  var isPolymorphic = (typeof params.polymorphic === 'string');
+
   if (!params.through) {
+    if (isPolymorphic) throw new Error('Polymorphic relations need a through model');
     var name1 = modelFrom.modelName + modelTo.modelName;
     var name2 = modelTo.modelName + modelFrom.modelName;
     params.through = lookupModel(models, name1) || lookupModel(models, name2) ||
@@ -1066,7 +1070,7 @@ RelationDefinition.hasAndBelongsToMany = function hasAndBelongsToMany(modelFrom,
   
   var options = {as: params.as, through: params.through};
   
-  if (typeof params.polymorphic === 'string') {
+  if (isPolymorphic) {
     options.polymorphic = params.polymorphic;
     var accessor = params.through.prototype[params.polymorphic];
     if (typeof accessor !== 'function') { // declare once
@@ -1113,6 +1117,16 @@ RelationDefinition.hasOne = function (modelFrom, modelTo, params) {
   var relationName = params.as || i8n.camelize(modelTo.modelName, true);
 
   var fk = params.foreignKey || i8n.camelize(modelFrom.modelName + '_id', true);
+  var typeTo;
+  
+  if (typeof params.polymorphic === 'string') {
+    var polymorphic = params.polymorphic;
+    fk = i8n.camelize(polymorphic + '_id', true);
+    typeTo = i8n.camelize(polymorphic + '_type', true);
+    if (!params.through) {
+      modelTo.dataSource.defineProperty(modelTo.modelName, typeTo, { type: 'string', index: true });
+    }
+  }
   
   var relationDef = modelFrom.relations[relationName] = new RelationDefinition({
     name: relationName,
@@ -1120,6 +1134,7 @@ RelationDefinition.hasOne = function (modelFrom, modelTo, params) {
     modelFrom: modelFrom,
     keyFrom: pk,
     keyTo: fk,
+    typeTo: typeTo,
     modelTo: modelTo,
     properties: params.properties,
     options: params.options
diff --git a/test/relations.test.js b/test/relations.test.js
index 11ffb97a..824d710f 100644
--- a/test/relations.test.js
+++ b/test/relations.test.js
@@ -528,6 +528,101 @@ describe('relations', function () {
   
   });
   
+  describe('polymorphic hasOne', function () {
+    before(function (done) {
+      db = getSchema();
+      Picture = db.define('Picture', {name: String});
+      Author = db.define('Author', {name: String});
+      Reader = db.define('Reader', {name: String});
+
+      db.automigrate(function () {
+        Picture.destroyAll(function () {
+          Author.destroyAll(function () {
+            Reader.destroyAll(done);
+          });
+        });
+      });
+    });
+
+    it('can be declared', function (done) {
+      Author.hasOne(Picture, { as: 'avatar', polymorphic: 'imageable' });
+      Reader.hasOne(Picture, { as: 'mugshot', polymorphic: 'imageable' });
+      Picture.belongsTo('imageable', { polymorphic: true });
+      db.automigrate(done);
+    });
+    
+    it('should create polymorphic relation - author', function (done) {
+      Author.create({ id: 8, name: 'Author 1' }, function (err, author) {
+        author.avatar.create({ name: 'Avatar' }, function (err, p) {
+          should.not.exist(err);
+          should.exist(p);
+          p.imageableId.should.equal(author.id);
+          p.imageableType.should.equal('Author');
+          done();
+        });
+      });
+    });
+    
+    it('should create polymorphic relation - reader', function (done) {
+      Reader.create({ id: 6, name: 'Reader 1' }, function (err, reader) {
+        reader.mugshot.create({ name: 'Mugshot' }, function (err, p) {
+          should.not.exist(err);
+          should.exist(p);
+          p.imageableId.should.equal(reader.id);
+          p.imageableType.should.equal('Reader');
+          done();
+        });
+      });
+    });
+    
+    it('should find polymorphic relation - author', function (done) {
+      Author.findOne(function (err, author) {
+        author.avatar(function (err, p) {
+          should.not.exist(err);
+          p.name.should.equal('Avatar');
+          p.imageableId.should.equal(author.id);
+          p.imageableType.should.equal('Author');
+          done();
+        });
+      });
+    });
+    
+    it('should find polymorphic relation - reader', function (done) {
+      Reader.findOne(function (err, reader) {
+        reader.mugshot(function (err, p) {
+          should.not.exist(err);
+          p.name.should.equal('Mugshot');
+          p.imageableId.should.equal(reader.id);
+          p.imageableType.should.equal('Reader');
+          done();
+        });
+      });
+    });
+    
+    it('should find inverse polymorphic relation - author', function (done) {
+      Picture.findOne({ where: { name: 'Avatar' } }, function (err, p) {
+        p.imageable(function (err, imageable) {
+          should.not.exist(err);
+          imageable.should.be.instanceof(Author);
+          imageable.name.should.equal('Author 1');
+          done();
+        });
+      });
+    });
+    
+    it('should find inverse polymorphic relation - reader', function (done) {
+      Picture.findOne({ where: { name: 'Mugshot' } }, function (err, p) {
+        p.imageable(function (err, imageable) {
+          should.not.exist(err);
+          imageable.should.be.instanceof(Reader);
+          imageable.name.should.equal('Reader 1');
+          done();
+        });
+      });
+    });
+    
+  });
+  
   describe('polymorphic hasMany', function () {
     before(function (done) {
       db = getSchema();