The occurrence of Clostridium difficile toxin in faeces has been studied in 53 inpatients with inflammatory bowel disease (IBD) at 57 admissions. Before faecal sampling of the patients had had sulphasalazine therapy--17 for more than 1 year--and 16 patients had taken antibiotics on 20 occasions within the last year. The toxin was found in 3 out of 57 samples (5%). In all cases it could be detected only in undiluted stool filtrate. None of the patients was treated for the C. difficile infection; remission was achieved in two of the patients, whereas the third patient with severe ulcerative colitis was referred to colectomy. Our results suggest that neither IBD as such nor long-term sulphasalazine therapy predisposes to occurrence of C. difficile toxin. Antibiotic therapy in these patients does not imply a higher risk of toxin occurrence than in other patients. In our region there is no need for routine screening for this in symptomatic patients with IBD.