Clinical observation was performed on the 71 hips of 52 patients which were replaced by total hip arthroplasty, who were treated at department of Orthopedic Surgery, College of Medicine, Kyungpook National University, from 1980 to 1985. The follow up period of each case varied from 2 to 7 years. The results obtained were as follows : 1. The peak age incidence ranged from 40 to 49 years, which was comprised 55.8%(29 patients) of total cases. Male was predominant(46 patients of total cases). 2. The cause of hip diseases were ; 49 cases of idiopathic avascular necrosis, which comprised highest incidence, 15 posttraumatic avascular necrosis, 4 osteoarthritis, 3 old pyogenic hip. 3. The lesion site were ; 23 right side, 10 left side and 19 both sides. All cases were Muller type which performed the Watson-Jones approach. 4. Seversl complications were developed; 1 subtrochanteric spiral fracture, 1 perforation of acetabulum, 1 perforation of femur shaft, 1 perforation of lesser trochanter of femur, 1 nerve palsy during the operation, post-operative superficial wound infection in 1 case, deep seated infection in 1 case, and wire breakage in 6 cases. 5. Preoperative and post-operstive functional evaluation by the Harris method was done ; 1) Average improvement was 49 points from 38.2 to 87.2 points. 2) Relief of pain was the most prominent effect of the total replacement surgery.