This study assessed the proportion of patients treated with anti-osteoporotic drugs during the 1-year period after hospitalization for a fracture, and the influence of a guideline in the period 1998-2000 on the likelihood of receiving treatment for osteoporosis after a fracture. Patients were assessed retrospectively for anti-osteoporotic drug use during a 1-year period following hospitalization for non-traumatic fracture. The PHARMO system, a population-based database ( n=865,000) containing drug and hospitalization data of community-dwelling inhabitants of defined areas in the Netherlands, was used. The study population comprised 1654 patients age 50 years and over who were admitted to hospital for a fracture resulting from a fall during the period 1998-2000. The treatment rate of newly treated patients and the change in treatment rate throughout the period 1998-2000 were the outcome measures. The majority of these patients were women (73%), and had femur fractures (51%). In total, 247 out of 1654 patients (15%) were prescribed anti-osteoporotic drugs within 1 year after discharge from the hospital. Of these 247 patients, 86 were newly treated, mainly with bisphosphonates in the year after discharge following the fracture, yielding a new treatment rate of 5%. The likelihood of receiving treatment for osteoporosis following fracture did not change with the calendar year of fracture (OR 0.95; 95% CI: 0.68-1.30). The result of this study shows that despite the introduction of an osteoporosis treatment guideline in 1999 recommending treatment for fracture patients, most of the time, fracture patients are not being treated for osteoporosis. Thus, to a large extent, osteoporosis remains under-treated.