Between January 1987 and September 1990, 67 consecutive cementless total hip arthroplasties were implanted in 59 patients by one surgeon. The mean age of the patients at surgery was 57 years (range, 23-80 years). All acetabular components were plasma-sprayed titanium hemispheric cups with four peripheral rim fins, but additional screw fixation was not used. The mean followup was 10.4 years (range, 8.8-12.5 years). With revision as the endpoint, the failure rate of this acetabular component at a mean of 10.4 years was 28% (19/67). Of the 56 patients (56 hips) with radiographic followup, loosening of the acetabular shell occurred in 10 hips in 10 patients (18%). Seventy percent of these loosened cups failed by tilt which occurred in a rapid manner; all of the patients required revision surgery. We examined the manner of loosening of a press-fit acetabular component after early (5-year) results showed high hip scores and a low failure rate.