We compared sulphasalazine (SSZ) toxicity in 140 patients (196 treatment periods) of two patient groups, those with rheumatoid disease (RD) (rheumatoid arthritis, RA, ankylosing spondylitis, AS), and those with inflammatory bowel disease (IBD). Adverse events occurred in 64% of all patients (highest 85% in AS and lowest 50% in ulcerative colitis, CU). There were more recorded adverse events in patients with RD than in patients with IBD. Hepatic side effects were more frequent in patients with IBD than in patients with RD. Adverse events were the most common reason for discontinuing the treatment (in 34.8% of AS patients, in 46.2% of RA patients, in 21.7% of the Crohn's disease patients and in 32.6% of CU patients). There were no lethal or permanent adverse events. Age, sex, rheumatoid factor and HLA-B27 antigen positivity did not influence on the appearance of adverse events.