Bisphosphonates are widely used for treatment of postmenopausal osteoporosis. Although short-term safety and efficacy of these drugs have been investigated and documented, an increasing number of recent reports draw attention to the possible correlation between long-term alendronate therapy and the occurrence of insufficiency fractures in the proximal femur owing to what is known as severely suppressed bone turnover. We describe two femoral insufficiency fractures in two women receiving long-term alendronate therapy. The first woman sustained a periprosthetic fracture at the tip of the femoral stem whereas the other woman had a fracture in the subtrochanteric region. We analyze the characteristics and natural course of these two unique fractures, and emphasize the importance of being aware of the possible correlation between long-term alendronate therapy and insufficiency femoral fractures.