67-Year-old woman who suffers diaphyseal fracture of the femur, with the history of intake of bisphosphonates for several years for its osteoporosis treatment. In the literature since relatively recently are articles describing spontaneous fractures associated with patients treated with biphosfonatos for several consecutive years (1, 2), a mechanism is not clear. These drugs lower the osteoclastic activity in bone metabolism, decreasing bone turnover and increasing mineral density, but raised the theory that the removal of bone turnover may be exaggerated and predispose to fractures. Despite the partnerships established in many studies, these continue to be circumstantial, it is required to continue with the investigations and case reports to arrive at a definitive conclusion.