Introduction: The complementary and alternative medications (CAM) usage among rheumatologic patients has grown during recent years. The aim of this study was to determine the Prevalence of CAM usage in rheumatologic patients in Kermanshah, Iran and to investigate its related factors. Materials and Methods: 500 patients with different rheumatic diseases were enrolled in this study. Following data was collected from the patients: age, sex, marital status, education level, whether they have regular visits by rheumatologist, type of rheumatic or musculoskeletal disease, disease duration, whether they use CAM and type of CAM, source of information to use these medications. Then obtained data was compared between the patients who used CAM and who did not. Results: The most common type of disease was rheumatoid arthritis (32.8%) followed by systemic lupus erythematosus (18.8%) and osteoarthritis (14%). Of the 500 participants (mean age: 46.28, 426 female), 109 patients (21.8%) reported that they have used CAM. The most frequently reported CAM was the herbal supplements (42.67%) followed by bloodletting and cupping (29.05%) Yoga and Meditation (7.43%), and special dietary regimens (7.43%). We found a relation between disease duration and usage of the CAM. Other factors were not associated with CAM usage. Conclusion: We found that patients with longer disease duration had more tendency to use CAM. This result may be important for the management of the increasing interest in CAM usage in rheumatologic patients.