A woman has been rescued from the Yarra River in Melbourne after she lost her grip on the blow-up doll she was riding.

A 19-year-old woman and a 19-year-old man were floating down the river in the city's north-east about 4.30pm yesterday using the inflatable dolls for buoyancy.

The woman lost her grip on the doll when they hit turbulent water, grabbing hold of a tree while yelling for help.

A kayaker took life jackets to the pair, who escaped injury and were rescued by the SES.