Background: The treatment of osteoporosis among postmenopausal women represents a major public health challenge because long-term therapy is needed to prevent fractures and chronic disability. Low patient compliance with prescribed osteoporosis treatments can severely distort the validity of controlled clinical trials. Raloxifene and alendronate have been shown to reduce the incidence of osteoporotic fracture in postmenopausal women in well-conducted randomized trials, but few data are available on the rate of adherence to these treatments in routine clinical practice.