The clinical and radiologic results of a consecutive series of 59 patients (69 hips) who had primary total hip arthroplasty using cementless prostheses was studied. Harris-Galante acetabular and femoral prostheses, which have a porous fiber-metal mesh coating intended to encourage bone ingrowth fixation, were used in all cases. Two femoral components were revised during the follow-up period, one for aseptic loosening and the other for late septic loosening. In the remaining 67 hips, the average Harris hip score rose from a preoperative 52 to 94 at the last follow-up examination (average follow-up period, 44 months). Eighty-eight percent of these hips had an excellent result (Harris hip score of 90 or more). Radiologic analysis demonstrated that all the acetabular components were stable. Eighty-three percent of the femoral components appeared to have stable bone ingrowth fixation, five components (7%) had stable fibrous ingrowth, and seven (10%) were unstable. Parallel radiodense lines were seen around the smooth portion of the stem in 93% of hips, but this finding appeared to have no clinical importance. Significant stress shielding of the proximal femur was seen in 16% of hips. Endosteal lysis of the distal femur occurred in 22% of hips, including large lesions in two patients who will require future revision surgery because of femoral diaphysis weakening. Femoral lysis was not associated with hip or thigh pain and was most common in young, male patients who had high activity levels.(ABSTRACT TRUNCATED AT 250 WORDS)