Periprosthetic bone loss is identified after inserting a hip prosthesis and is many times a result of stress shielding or altered loading of the proximal femur. Depending on the severity, the bone loss may threaten the prosthesis survival. The current study investigated the effect of cyclic etidronate therapy on periprosthetic and contralateral bone mineral density (BMD) in an one-year, prospective, randomized, double-blind study on 46 patients after cemented hip arthroplasty. Etidronate was administered orally in a regimen repeated every 14 weeks and periprosthetic BMD was measured with dual energy X-ray absorptiometry (DXA) in the total periprosthetic area and in the seven Gruen Zones at 1 week (baseline), 6 weeks, 3 months, 6 months, and 12 months postoperatively. In the etidronate group there were significant temporal BMD decreases measured in Gruen Zones 2, 3, 6, and 7 as well as in the entire proximal femur; the greatest decrease was 11.1% and was measured in Zone 2 at 12 months. Also in the etidronate group, there was a significant 3.4% increase in BMD of the spine at 12 months. In the placebo group there were significant temporal BMD decreases measured in Gruen Zones 1, 2, 3, 4, 6, and 7 as well as in the entire proximal; the greatest decrease was 16.4% and was measured in Zone 7 at 12 months. There were no significant differences between the mean BMD measurements of the etidronate and placebo groups with the exception of the mean percent change in the spine at 6 months and 12 months, and in Gruen Zone 3 at 6 months; in all three cases the etidronate group had significantly greater mean values. These findings suggest that cyclic etidronate therapy has no significant effect in surpressing the periprosthetic bone loss following cemented hip arthroplasty.