The results of eighty-three consecutive primary total hip arthroplasties in which a Harris-Galante porous-coated acetabular component had been used were reviewed after a minimum of five years. In all patients, the stated diameter of the acetabular component (the diameter printed on the packaging for the implant) used was equal to the stated diameter of the reamer (the diameter printed on the reamer) that had been used last in the preparation of the acetabulum. As there was little or no press-fit stability, stability was obtained initially with multiple transfixing screws. No component was revised because of loosening, and none were radiographically loose at an average of sixty-eight months and a maximum of seven years after the operation. There was no evidence of disruption of the titanium porous mesh, and no screw had bent or broken. Two sockets, however, had been revised because of failure of the liner-locking mechanism as well as disassociation of the polyethylene liner from the titanium-alloy shell. Lysis of bone occurred in only one patient, around one screw. Areas of non-contact (gaps) between the porous mesh at the periphery of the acetabular component and the bone were seen on the immediate postoperative radiographs of nearly half of the patients. New areas of radiolucency, which had not been seen immediately postoperatively, were identified at two years in forty-nine hips. These radiolucent lines were never wider than one millimeter and were most frequently located in zone 3 and, less frequently, in zone 1. At the time of the most recent follow-up evaluation, a progressive radiolucent line was identified around twenty-two components and a discontinuous radiolucent line was present in all three zones around eleven components. No continuous radiolucent line was identified at the mesh-bone interface of any component. These results are superior to our results with cemented acetabular components after a similar period of follow-up. A longer period of follow-up is needed before the importance of these thin radiolucent lines can be determined, but experience with cemented acetabular components indicates that progressive or extensive radiolucent lines, or both, may represent resorption of bone at the porous mesh-bone interface and this can lead to loosening of the component. Our data suggest that the technique used for implantation may be important not only for the initial fixation and ingrowth of bone, but also for the long-term durability of the fixation of a porous-coated acetabular component.(ABSTRACT TRUNCATED AT 400 WORDS)