Collagenous colitis is characterized by chronic watery diarrhea and a greater than 10 micron-thick collagen deposit in the subepithelial layer of the colonic mucosa. Rheumatic and autoimmune diseases have been reported to occur in patients with collagenous colitis. In 1993, we managed four patients with collagenous colitis and joint diseases. One had rheumatoid arthritis, one had a spondylarthropathy and two had seronegative polyarthritis without joint destruction. Three patients had dryness of the eyes and/or mouth and two had Raynaud's phenomenon. These four cases and data from a literature review provide a basis for discussing possible links between collagenous colitis and a number of joint diseases. Although some anecdotal case-reports may reflect a chance association with inflammatory joint diseases, available evidence suggests that collagenous colitis may be a cause of enteropathic arthropathy. Recent data point to an abnormality in the differentiation of fibroblasts in the colonic mucosa, although the mechanism that initiates this abnormality remains unknown.