We evaluated the usefulness of various parameters in predicting the prognosis of ulcerative colitis. The records of 73 patients with ulcerative colitis were examined retrospectively. Patients were divided into two groups according to whether they had received only 5-aminosalicylic acid (5-ASA; n = 26) or glucocorticoids and/or azathioprine with or without 5-ASA (n = 47). The disease extent, endoscopic activity and ulcerative colitis activity index (UCAI) before therapy were recorded, together with the disease outcome. No statistically significant differences in outcome were observed in relation to therapy group, disease extent or endoscopic activity. UCAI had a significant effect on outcome, however: patients with lower UCAI values were more likely to remain in remission and less likely to require urgent surgery or experience a fatal outcome than those with higher UCAI values. This difference was apparent in both treatment groups. Thus a high pre-treatment UCAI may indicate a worse outcome.