During the last 20 years almost 3000 uncemented total hip replacements have been used in the treatment of osteoarthritis and rheumatoid arthritis. The development of an axially located prosthesis is outlined, and the causes of failure indicated. Uncemented prostheses have the advantage of a relatively low mortality and morbidity and the rate of infection in particular is low. Interface pain, with or without frank prosthetic loosening, is the commonest cause of failure, but revisional surgery is relatively easy, and usually successful. Loss of function without significant pain may occur after many years from distal migration of the femoral component. The development of an uncemented metal-on-plastic joint has produced better short-term results than the metal-on-metal articulation, probably because of its lower frictional coefficient and the use of a wider range of pelvic and femoral components.