Skin diseases have been shown to worsen psychological distress, which, in turn, may be detrimental to treatment outcomes. Both the impact of psychological distress on response to treatment in mycosis fungoides (MF) and the effect of treatments on psychological well-being are unclear. To evaluate (1) the association between pretreatment psychological morbidity and treatment outcome in early-stage MF and (2) the impact of response to treatment on psychological well-being. This was a prospective cohort study of patients with early-stage MF who started a new stage-directed treatment for their disease. The response was determined using the modified severity-weighted assessment tool, and psychological distress was assessed using the 12-item General Health Questionnaire (GHQ-12) and Penn State Worry Questionnaire (PSWQ). Participants were followed for 1 year. In all, 24 consecutive patients were recruited. Objective response rate was 71% (17/24), consistent with existing literature. Prior to treatment, 9 patients (38%) had clinically significant psychological distress on the GHQ-12, while 8 (33%) demonstrated high-level worry on the PSWQ. Of these patients, 6 had pathologic scores on both instruments. Patients with significantly less baseline anxiety/depression on the GHQ-12 responded better to treatment than patients with higher levels (P = .004). In addition, responders' mean GHQ-12 scores decreased by 39% and their PSWQ scores by 17%, whereas nonresponders' GHQ-12 scores increased by 93% (P = .042) and their PSWQ scores by 11% (P = .019). These findings suggest that (1) baseline psychological distress is associated with worse outcomes in patients with early-stage MF and that (2) effective treatment improves psychological morbidity.