Though the Selkirk Rex is similar in name to the Cornish Rex and Devon Rex, it is a different breed in both genetics and coat. Kittens give clues early on as to their coat, they are born curly or straight and do not change as they get older as the gene is dominant in this breed; curly coated kittens will always be curly and straight coated kittens will not develop curls. The best coats are found on mature males and spayed females, with the best display of curl occuring on flanks, tummy and neck; the back has the least amount of curl. The Selkirk Rex has two coat lengths, short and long, both lengths have different requirements. A short coat should be soft, plushy, full and curly; dense with no bald or thinly covered areas. The hair should stand out from the body and not appear flat. Curling should be random and unstructured, arranged in loose curls that appear as clumps rather than waves and should affect the whole coat. The tail should be plush and the hair should lie compactly.
The long coat should be soft, full and curly, and though it should not appear nor be as plush as the short coat, it should not appear thin. Curls should appear as clumps or ringlets rather than waves. The tail should be plumy with hair that stands slightly away. The coat can come in any possible color or color combination.
The head of the Selkirk Rex should be round, broad, and full cheeked in both genders, the muzzle of medium width and chin firm with level or scissor bite. Ears should be medium in size, tapered and set well apart fitting into the rounded contours of the head. Furnishings should be curly if present. Eyes should be large and round giving a sweet, open expression; they should not appear almond or oval shaped.
Selkirk Rex's have a medium to large body that is well-balanced with a rectangular torso that is not too long. Legs should be medium to long with substantial boning, and should be in proportion to the body, ending in large, round and firm feet.