Objective. To find the prevalence of musculoskeletal complaints and rheumatic disorders in Iran. Methods. Tehran, with one-ninth of the population of Iran and of mixed ethnic origins, was selected as the field. Subjects were randomly selected from the 22 districts. Interviews were conducted once a week, on the weekend. The 3 phases of stage 1 were done on the same day, in parallel, like the fast-track Community Oriented Program for Control of Rheumatic Diseases (COPCORD). Results. Four thousand ninety-six houses were visited and 10,291 persons were interviewed. Musculoskeletal complaints during the past 7 days were detected in 41.9% of the interviewed subjects. The distribution was: shoulder 14.5%, wrist 10%, hands and fingers 9.4%, hip 7.1%, knee 25.5%, ankle 9.8%, toes 6.1%, cervical spine 13.4%, and dorsal and lumbar spine 21.7%. Degenerative joint diseases were detected in 16.6% of subjects: cervical spondylosis 1.8%, knee osteoarthritis (OA) 15.3%, hand OA 2.9%, and hip OA 0.32%. Low back pain was detected in 15.4% and soft tissue rheumatism in 4.6%. Inflammatory disorders were rheumatoid arthritis 0.33%, seronegative spondyloarthropathies 0.23%, ankylosing spondylitis 0.12%, systemic lupus erythematosus 0.04%, and Behcet's disease 0.08%. Fibromyalgia was detected in 0.69% and gout in 0.13% of the studied population. Conclusion. The large urban COPCORD study in Iran showed a high prevalence of rheumatic complaints in the population over the age of 15 years, 41.9%. Knee OA and low back pain were the most frequent complaints.