Patients with ulcerative colitis tend to be young, potentially at peak lifetime productivity levels, and the disease can be devastating in its effects on the quality of life in these individuals. No treatment for ulcerative colitis can be comprehensively evaluated without careful attention to its impact on such psychosocial issues. The quality of life was evaluated in 374 ulcerative colitis patients using mesalamine capsules at 1 g, 2 g, and 4 g daily versus placebo in an 8-week, randomized, dose-response, placebo-controlled, double-blind, multicentre trial. Function-related quality of life parameters were assessed in this study, including five pertinent clinical symptoms and seven general life capabilities. These parameters have been previously shown to be valid, reliable, and responsive to the disease activity of ulcerative colitis. All of the parameters were recorded using a 10-cm visual analogue scale, except trips to the toilet which were recorded in patients' diaries. The mean change was calculated from baseline and endpoint data. Mesalamine at 2 g and 4 g daily was significantly superior to placebo in improving each of the 12 quality of life parameters (P < 0.05). These results indicate that controlled-release mesalamine significantly enhances the quality of life for patients with either left-sided ulcerative colitis or pancolitis.