Backgrounds: Statins are associated with several muscle complaints, such as: myositis, myalgia, muscle weakness, muscle spasms and rhabdomyolysis. Age, race, gender, dose of statin, concomitant medications, concomitant disorders and genetics have been reported as the most important risk factor for statin-induced myalgia. The aim of this study was to determine the prevalence and associated risk factors of atorvastatin-induced myalgia in hospitalized patients in Tehran, Iran. Methods: In this cross sectional study, a questionnaire was developed by expert panel opinions. The questionnaire was included various items regarding demographic data and myalgia evaluation factors. Seven hundred patients were included in the study and necessary data were gathered. Finally, the data were analyzed and a statistical model was designed to predict the myalgia risk factors. Results: The rate of myalgia was 44.3% among studied patients. By developing a multivariate logistic model, female gender (OR= 0.47, P-value