Recently, there is some enthusiasm for using cementless system in THRA with the rationale that biologic fixation will avoid the problem of loosening as experienced in cemented system. But long term results of cementless THRA have not proved the better result than cemented one at the present time. The effects of stress shielding with proximal bony resorption and more difficulty in stem extraction for revision cases are the newly encountered problems which should be solved. From September 1984 to June 1989, we have operated 93 hips with cementless system of European design (Mittelmeier and P-M type) exclusively, which has some common features of conical shaped threaded acetabular component and macroporous press-fit straight stem. Among them, 50 hips in 39 patients could be analyzed radiologically and clinically with mean follow-up period of 2 years and 4 months ; the longest 4 years and 10 months, the shortest 1 year. The results were as follows;1. The average preoperative Harris hip score, 47.5, was increased to 86.3 at final follow-up and the average D'Aubigne 6-point pain score was 5.0 at final follow-up. 2. Better radiological results were obtained in the good initial fit group, and the results were not correlated with bone quality scale and initial position of implants. 3. Mittelmeier type showed less frequent rate of radiological loosening than PM type, even though not influenced by the differences in bone quality scale, initial fitness and position of implants between two groups. 4. Four stems (31%) among 13 stems of radiological loosening, and 5 cups (36%) among 14 cups of radiological loosening, were coincided with clinical symptoms:The evidence of radiological loosening without clinical symptom with good Harris hip score were more commonly observed finding.