Background: There is controversy about the relationship between vitiligo and thyroid dysfunction. Objective: To evaluate the relationship between vitiligo and thyroid disorders. Patients and Methods: This was a case-control study carried out on individuals with vitiligo in 2004 in Zahedan, that had it for at least 6 months as cases and individuals without vitiligo considered as the control group (Age and sex were matched with case group). T3, T4, TSH, T3RU in both groups were assessed and FTI was calculated. Then hypo-, hyper- and euthyroid states were determined based on FTI and T3 level (For T3 hyperthyroidism) and data were analyzed by conditional logistic regression. Results: Each study group consisted of 50 individual, 52% female and 48% male. In the patient group, 16% had thyroid dysfunction, 14% of which had hyperthyroidism and 2% hypothyroidism. In control group, 4% had thyroid dysfunction, 2% of which had hyperthyroidism and 2% hypothyroidism. In case group only one patient had signs and symptoms of hyperthyroidism but in control group none had clinical symptoms. With statistical analysis was done odds ratio=7 (P<0.05) and the difference was significant. Conclusion: Vitiligo patients should be evaluated for thyroid dysfunctions to prevent complications of thyroid disease.