Alendronate has been shown to prevent osteolysis in a canine total hip arthroplasty (THA) model. However, the effect of alendronate on bone ingrowth and remodeling around canine cementless hip replacement components remains unclear. We hypothesized that oral alendronate would increase net bone ingrowth into the porous surface of THA components when intimate bone/implant contact exists. To test this hypothesis, six mature dogs received unilateral cementless THA and were treated with five milligrams of oral alendronate daily from day seven to day eighty-four postoperatively. Six comparable dogs served as controls. Quantitative analysis of net bone ingrowth into the porous surface did not show a significant difference between the two groups, (control 7.9 +/- 1.5, alendronate 7.5 +/- 1.4, P < 0.6). These results did not support the hypothesis that oral alendronate would increase net new bone formation into the porous surface of THA components. Key words: alendronate, bone ingrowth, total hip arthroplasty.