PURPOSE: This study was conducted to evaluate the development of osteolysis and the outcome of performing primary total hip arthroplasty using a non-cemented Multilock femoral stem with a proximal circumferential porous coating. The patients were followed up for a minimum of five year and we include the follow-up clinical and radiological results. MATERIALS AND METHODS: We reviewed the clinical and radiological results of 44 total hip arthroplasties in 40 patients, and these patients were available for a minimum of 5 years follow-up (average: 90.6 months), A Multilock femoral stem and Harris-Galante II acetabular component was used in all the operations, and the operations were performed between June 1993 and February 1997. RESULTS: The average Harris hip score improved from 54.5 points preoperatively to 91.5 points postoperatively. The stability of the femoral stem, based on Engh's evaluation schema, showed stability with osseous ingrowth being noted in 43 cases (98%), stability with fibrous ingrowth being noted in 1 case (2%), and there was no unstable fixation. Femoral osteolysis occurred in 17 cases (38%), which was mostly restricted to zones I and VII. Acetabular osteolysis occurred in 9 cases (20.5%), with zone II being the most common location. There were no cases of femoral stem revision. 7 cases of acetabular revision were done due to polyethylene liner dissociation in 3 cases and osteolysis of a large area in 4 cases. The mean revision period was 73 months (range: 37~112) from the initial operation. CONCLUSION: The femoral stem was devised to press fit through the circumferential proximal porous coating and the flute type distal stem has the benefit of excellent fixation and prevention of particle invasion to the distal bone canal, which is caused by proximal bone ingrowth. However, the frequency of revision was great due to the increased rate of wear by the structural defect of the Harris-Galante type II acetabular cup and the high occurrence of osteolysis.