Current first-line treatment of ulcerative colitis consists of a combination of mesalazine enemas and oral mesalazine; however, many patients may discontinue mesalazine enemas. In this single-center, cross-sectional study, 165 outpatients with ulcerative colitis completed a self-administered questionnaire regarding the frequency of mesalazine enemas, difficulties in performing these enemas, and factors possibly associated with their discontinuation, as well as patient clinical and demographic characteristics. Of 165 patients, 34 (20.6%) discontinued mesalazine enemas because of a lack of efficacy. Five of the 13 items assessing difficulties were answered affirmatively by the majority of patients. Discontinuation of enema application was associated with a perceived lack of efficacy, four or more bowel movements per day, and lower scores on measurement of the doctor–patient relationship. Application of mesalazine enemas by patients with ulcerative colitis may be improved by discussions with peers and healthcare professionals and by adjusting the frequency of application or the time of starting the enema based on worsening of ulcerative colitis.