A follow-up study was made of 94 primary total hip arthroplasties in 86 patients with a Harris-Galante (Zimmer, Warsaw, IN) porous-coated femoral component implant to determine the change in prevalence of femoral lysis and its clinical significance. At a mean follow-up period of 53 months (range, 16-86 months), femoral lysis was present in 31% of the femurs. In the first report of this condition, the incidence was 3%. The mean patient age was 54 years (range, 30-69 years). The most common diagnosis was osteoarthritis (62 hips). Of the 29 hips with femoral lysis, 11 were graded as extensive. Of the 14 hips in which the femoral component was defined as loose, 12 had femoral osteolysis; however, the mean Harris hip score among those with lysis was not reduced in those with femoral osteolysis (88 compared with 90 the entire group). Pelvic osteolysis, in contrast, was present in only one hip, around a screw. In this series, femoral lysis was a major complication, whether the femoral component was stable or not, and the prevalence of lysis increased sharply over time.