The aetiology of ulcerative colitis (UC) is unknown. However, much interest has been devoted recently to the relationship between appendicectomy and ulcerative colitis. A case-control study was conducted, comparing appendicectomy rates between 110 patients with UC (group 1) and 136 patients attending an orthopaedic clinic free from UC (group 2). The appendicectomy rates were 0.9% (group 1) and 10.3% (group 2), respectively (P < 0.002). The present study shows that patients with ulcerative colitis had rarely undergone appendicectomy before the first manifestation of colitis. Further research on this relationship is called for.