The Rex coat mutation occurred in 1970 although it is unclear in which country it first occurred. The Rex mutation causes the coat to curl slightly so that the hairs are lifted away from the body. This gives a Short Haired Hamster a thick plush looking coat and on a Long Haired Hamster can cause the coat to appear a little unkept. The Rex mutation also causes the whiskers to become curly.

Rex can be combined with Short Haired, Long Haired and Satin.