diff --git a/lib/context.js b/lib/context.js
index 95681a0..8eb6a85 100644
--- a/lib/context.js
+++ b/lib/context.js
@@ -226,6 +226,11 @@ class ContextSession {
       await this.remove();
       return;
     }
+    if (session._requireRegenerate) {
+      await this.remove();
+      if (this.store) this.externalKey = opts.genid && opts.genid(ctx);
+      session.save();
+    }
 
     const reason = this._shouldSaveSession();
     debug('should save session: %s', reason);
diff --git a/lib/session.js b/lib/session.js
index c9019af..13a50fe 100644
--- a/lib/session.js
+++ b/lib/session.js
@@ -134,6 +134,9 @@ class Session {
     await this._sessCtx.commit();
   }
 
+  regenerate() {
+    this._requireRegenerate = true;
+  }
 }
 
 module.exports = Session;
diff --git a/test/cookie.test.js b/test/cookie.test.js
index 462e56b..d771029 100644
--- a/test/cookie.test.js
+++ b/test/cookie.test.js
@@ -674,6 +674,48 @@ describe('Koa Session Cookie', () => {
     });
   });
 
+  describe('ctx.session.regenerate', () => {
+    it('should change the session key, but not content', done => {
+      const app = new App();
+      const message = 'hi';
+      app.use(async function(ctx, next) {
+        ctx.session = { message: 'hi' };
+        await next();
+      });
+
+      app.use(async function(ctx, next) {
+        const sessionKey = ctx.cookies.get('koa.sess');
+        if (sessionKey) {
+          await ctx.session.regenerate();
+        }
+        await next();
+      });
+
+      app.use(async function(ctx) {
+        ctx.session.message.should.equal(message);
+        ctx.body = '';
+      });
+      let koaSession = null;
+      request(app.callback())
+      .get('/')
+      .expect(200, (err, res) => {
+        should.not.exist(err);
+        koaSession = res.headers['set-cookie'][0];
+        koaSession.should.containEql('koa.sess=');
+        request(app.callback())
+        .get('/')
+        .set('Cookie', koaSession)
+        .expect(200, (err, res) => {
+          should.not.exist(err);
+          const cookies = res.headers['set-cookie'][0];
+          cookies.should.containEql('koa.sess=');
+          cookies.should.not.equal(koaSession);
+          done();
+        });
+      });
+    });
+  });
+
   describe('when get session before enter session middleware', () => {
     it('should work', done => {
       const app = new Koa();
diff --git a/test/store.test.js b/test/store.test.js
index caf5375..be3a5fe 100644
--- a/test/store.test.js
+++ b/test/store.test.js
@@ -544,6 +544,48 @@ describe('Koa Session External Store', () => {
     });
   });
 
+  describe('ctx.session.regenerate', () => {
+    it('should change the session key, but not content', done => {
+      const app = new App();
+      const message = 'hi';
+      app.use(async function(ctx, next) {
+        ctx.session = { message: 'hi' };
+        await next();
+      });
+
+      app.use(async function(ctx, next) {
+        const sessionKey = ctx.cookies.get('koa.sess');
+        if (sessionKey) {
+          await ctx.session.regenerate();
+        }
+        await next();
+      });
+
+      app.use(async function(ctx) {
+        ctx.session.message.should.equal(message);
+        ctx.body = '';
+      });
+      let koaSession = null;
+      request(app.callback())
+      .get('/')
+      .expect(200, (err, res) => {
+        should.not.exist(err);
+        koaSession = res.headers['set-cookie'][0];
+        koaSession.should.containEql('koa.sess=');
+        request(app.callback())
+        .get('/')
+        .set('Cookie', koaSession)
+        .expect(200, (err, res) => {
+          should.not.exist(err);
+          const cookies = res.headers['set-cookie'][0];
+          cookies.should.containEql('koa.sess=');
+          cookies.should.not.equal(koaSession);
+          done();
+        });
+      });
+    });
+  });
+
   describe('when store return empty', () => {
     it('should create new Session', done => {
       done = pedding(done, 2);