Total hip replacement arthroplasty has been popularized since Sir John Charnley introduced lowfrictrion arthroplasty and used self-curing bone cement from November 1962, but cemented total hips showed a lot of problems of which the most serious one is high incidence of aseptic loosening of components in long term follow-up. To combat against this complication, many types of cementless total hips have been developed and used clinically during the past 10 to 15 years with continuing modification. Forty-four hips were replaced with Mittelmeier's Autophor ceramic total hips in 38 patients from March 1983 to December 1985 at the Our Lady of Mercy Hospital, Catholic University Medical College. Among these hips, 13 hips of 11 patients which were followed-up more than 5 years had been observed radiologically for aseptic loosening. The follwing results were obtained. 1. The average age of the patients was 43 years and 6 months, and the average follow-up period was 6 years and 4 months (from 5 years to 8 years and 5 months). 2. The cup inclination was changed by 4.5°to 10.0°(average, 6.7°) in 7 cases (53.8%). 3. The acetabular cup migrated medially 2.0 to 4.5 mm (average, 2.9 mm) in 5 hips (38.5%) and superiorly 4.5 to 11.0 mm (average, 8.2 mm) in 11 hips (84.6%). As a result, one or both of the significant medial and upward migrations were noted in 12 hips (92.3%). 4. A radiolucent zone of 1.5 to 7.0 mm (average, 4.9 mm) was noted mainly at the inferomedial aspect of the cup in 10 cases (7.6.9%). 5. Stem subsidence was 4.0 to 17.5mm (average, 9.3mm) in all hips(100%), and the stems changed their positions in the medullary canal in 8 hips (61.5%). Radiolucent zone around the stem was 1.5 to 7.0mm (average, 4.3 mm) of thickness in 12 hips (92.3%).