BACKGROUND There are few studies on the effect of acetabular cup design on cement penetration. METHODS We evaluated the effects of an acetabular flange on cement pressurization and cement penetration in 12 cadavers. Flanged or unflanged cups were implanted in paired human acetabula with simulated intraosseous bleeding pressure but without cement pressurization before insertion of the cup. Three pressure transducers were used to record intra-acetabular peak and average pressures during cup insertion. Following implantation, the whole specimens were AP-radiographed and standardized sections through the acetabula were microradiographed to evaluate cement penetration. RESULTS Flanged cups produced greater intra-acetabular peak pressures than unflanged cups, but did not increase the average intra-acetabular pressure. Cement penetration did not differ significantly between the two groups. CONCLUSIONS Our findings do not support the use of flanged cups as the sole means of cement pressurization in the acetabulum.