To determine (1) the prevalence of candidal carriage in patients with oral mucosal disease to be treated with topical immunosuppressive therapy, and (2) the incidence of oral candidiasis among carriers and noncarriers after initiation of therapy to assess any correlation between carriage and the development of candidiasis. Records of patients who underwent swab cultures for Candida between January 2009 and October 2014 at the Brigham and Women's Hospital in Boston, Massachusetts, were retrospectively reviewed. The prevalence of candidal carriage and incidence of candidiasis were determined by using descriptive statistics. Of 99 evaluable patients, 20 (20.2%) were Candida positive and 79 (79.8%) were Candida negative. Of 44 patients with follow-up, 7 (15.9%) were Candida positive and 37 (84.1%) were Candida negative; five (11.4%) developed candidiasis. Four of seven (57.1%) Candida-positive patients developed candidiasis, whereas only one of 37 (2.7%) Candida-negative patients developed candidiasis (P=.0012). The overall prevalence of candidal carriage was low (20.2%), and there was a significant difference in the incidence of candidiasis between carriers and noncarriers (P=.0012) after topical immunosuppressive therapy. Therefore, patients who are candidal carriers should be monitored closely for the development of secondary candidiasis and may be candidates for prophylactic antifungal therapy.