The curl in their fur is caused by a different mutation and gene than that of the Cornish Rex and German Rex, and breeding of a Devon to either of those cats results in cats without rexed (curled) fur.

Devons, which are medium sized cats, are often called "pixie cats" or "alien cats" because of their unique appearance. Their uncommonly large ears are set low on the sides of their wide heads, their eyes are large, and their noses are slightly upturned. Their body type is distinctly lightly-built.

The typical Devon is active, mischievous, playful, and very people-oriented. They're relatively easy to take care of, but they do shed, and many of those with allergies have found that they are not always hypoallergenic.