Background: Vitiligo is a common autoimmune skin disease that may occur in association with other autoimmune disorders especially those of the endocrine system. Diabetes mellitus is a common endocrine disease associated with vitiligo. Objective: To study the association of vitiligo and diabetes mellitus. Patients and Methods: In this descriptive cross-sectional study, 750 diabetic patients referred to Mashhad Diabetes Center were studied in Shahrivar 1380. Results: Thirty-two (4.3%) of these patients suffered from vitiligo that mostly was of generalized type. The face was the most common site of involvement. Twenty-two patients (68.7%) were female and 10 patients (31.3%) were male. Five percent of female and 3.3% of male diabetics suffered from vitiligo. 4.2% of NIDDM diabetics and 4.7% of IDDM diabetics suffered from vitiligo. Conclusion: Vitiligo was more common in NIDDM than IDDM because of the higher prevalence of NIDDM, but the association of vitiligo with IDDM was stronger. Vitiligo was more common in female than male diabetics.