The displaced femoral neck fractures remain a major challenge to orthopaedic surgeons as the elderly population is increasing. Successful union by internal fixation after adequate reduction without avascular necrosis is primary goal since the functional results having own femoral head are much superior to those having prosthetic femoral head, but prosthetic replacement is indicated for some patients with fresh fractures who need early ambulation as well as neglected fractures and failed internal fixations. The early result after prosthetic replacement was known to be very satisfactory but the late complications are becomming the major problem. Authors reviewed 21 cases of the prosthetic replacements for the femoral neck fractures which were followed for more than one year and managed at Fatima Hospital during the years between 1975-1984 and the following results were obtained. 1. The cases were 8 males and 13 females having ages from 42 to 87 years with average 69 years old. 2. The cases were 11 elderly fresh fractures, 6 neglected fractures, 2 failed osteosynthesis and 2 others. 3. Moore and Thompson prosthesis were used and 13 of them were fixed with bone cement. 4. The early result evaluated at 3 months after surgery revealed satisfactory in 90% but the final result at average 3 years and 5 months ranging from 1 year to 6 years and 2 months revealed satisfactory results in 58% 5. There was no significant early post-operative complications. 6. The late complications were 8 cases of acetabular erosions and these were combined with stem loosening in 2, subsidence in 2 and deep infection in 1 case. 7. The late complications started to reveal at about 3 years after surgery and occurred in younger and active patient. 8. The prosthetic replacement for femoral neck fracture is recommended for the inactive patient or the patient with expected activity less than 3 years.