The prevalence of musculoskeletal system complaint and involvement in a group of 54 Crohn's disease patients, with a follow-up of 2 to 40 years, was studied and compared to that of a control group of patients with a similar distribution of sex and age. Twenty-four (44%) with Crohn's disease complained of arthralgia in various joints, but only 7.4% had objective findings compatible with joint pathology such as swelling, tenderness, and decreased range of motion. None of them had any serological or radiological evidences of joint damage. No significant correlation was found between patients' complaints/physical signs and age, sex, duration, or severity of Crohn's disease or mode of medical or surgical treatment. In the control group, 46% complained of arthralgia in various joint. The differences in the percentages of arthralgia between the two groups was not significant, although they differed in location of the affected joint. In the Crohn's disease group, a significantly higher proportion of knee, hip, and wrist involvement was observed, while backache was very common in the control group. It is suggested that arthritis in patients with Crohn's disease is an uncommon finding and that arthralgia is just as prevalent as in a matched control group. The pathogenesis of arthralgia in such a condition may be caused by soft tissue involvement.