Most breeds of cat have three different types of hair in their coats: the outer fur or "guard hairs", which is about 5 cm long in shorthairs and 10cm+ long in longhairs, a middle layer called the "awn hair", and finally the down hair or undercoat, which is very fine and about 1 cm long. Cornish Rexes have only the undercoat.

The coat of a Cornish Rex is extremely fine and soft to the touch. However, their light coat means that they are only suitable for indoor living in moisture free and warm conditions. Consequently, these cats tend to hang around light bulbs, the tops of computer monitors, and other warm places. Cornish Rexes also have a cheesy smell peculiar to the breed - this odour comes from scent glands in the paws.

The Cornish Rex is an adventurous cat. As the Rex is intelligent, it can readily adapt to new situations and engage in explorative behaviour. Humans often consider this behaviour to be deliberately mischievous, but this is a case of anthropomorphism. The Rex seeks out the company of people, and is friendly towards other companion animals. It is a suitable pet for timid children.

Origin

The Cornish Rex is a genetic mutation that originated from a litter of kittens born in the 1950s on a farm in Cornwall, UK (hence their name). One of the kittens, Kallibunker, a cream colored male, had an extremely unusual, fine, curly coat, and he became the first Cornish Rex.

There is another very similar breed — the Devon Rex. Devon and Cornish Rexes are produced by different genes, and crosses between the two are not allowed in pedigrees, nor will they produce a cat with the short wavy fur if mated together. Another hair-deficient breed is the Sphynx cat.

Though some people believe that the short hair of the Cornish Rex makes them non or hypo-allergenic, this is absolutely not accurate. Most people who have cat allergies are allergic to cat dander, and cat saliva. Since Cornish Rex cats groom as much or even more than cats with all types of hair in their coat, the Cornish Rex cat still produces an allergic reaction in people who are allergic to cats. However, due to the low amount of fur shed from these cats, people with only slight allergies may experience fewer symptoms with a Rex.

The word "Rex" implying short or otherwise unusual fur comes from a rabbit breed. King Albert of the Belgians (1875 – 1934) once entered some short-haired rabbits in a rabbit show. The rabbits didn't meet the breed standard. Not wanting to offend the king, the show officials accepted them, but wrote "rex," meaning "king" by their names.