['Although aminosalicylic acid (ASA) preparations have been used as first-line drugs for the treatment of ulcerative colitis (UC), no consistent view has been established regarding the ASA dose during the remission-maintenance phase of the disease. In this study, we examined whether the ASA dose should be reduced during the remission-maintenance phase.', 'This study included 203 patients in the remission-maintenance phase of UC. The Mayo endoscopic subscore (MES) was used to evaluate mucosa. Comparison and analysis were performed between patients whose ASA dose had been unchanged and whose dose had been reduced, between patients with endoscopic healing (EH) group and those without endoscopic healing (WEH) group, and between patients with an MES of 0 and 1.', 'Comparison between the unchanged-ASA and reduced-ASA groups revealed that the remission-maintenance rate was higher in the unchanged-ASA group (p\u2009<\u20090.001). Next, the remission-maintenance rate was higher in the EH/unchanged-ASA group than in the EH/reduced-ASA group (p\u2009=\u20090.042). Comparison between the MES 0 and 1 groups revealed that the remission-maintenance rate was higher in the MES 0 group (p\u2009=\u20090.007). In addition, no significant difference in remission-maintenance rates was observed between the MES 0/unchanged-ASA group and the MES 0/reduced-ASA group (p\u2009=\u20090.108).'] Does timing for dose-down of 5-ASA depend on mucosal status with ulcerative colitis?