Lichen sclerosus is a relatively common chronic inflammatory skin disease that predominantly affects the anogenital area. Accumulating evidence indicates that lichen sclerosus in women may be associated with other autoimmune disease, whereas this association seems to lack in male patients. We retrospectively evaluated the prevalence of autoimmune diseases and serological parameters indicative for autoimmunity in male and female patients with lichen sclerosus. Of the 532 patients (396 women, 136 men; 500 adults, 32 children; mean age: 49 years; range 1-89 years; female:male ratio 3:1), 452 (85%) had genital and 80 (15%) had extragenital disease. In women, lichen sclerosus was significantly more often associated with at least one autoimmune disease as compared to men (odds ratio [OR] 4.3, 95% confidence interval [CI] 1.9-9.6; p<0.0001). Moreover, female patients with lichen sclerosus had sinificantly more often associated autoimmune thyroid diseases (OR 4.7, 95% CI 1.8-11.9; p<0.0002), antithyroid-antibodies (OR 2.7, 95% CI 1.1-6.5; p=0.023), and elevated autoantibodies (OR 4.1, 95% CI 1.9-9.3; p<0.0001) as compared to male patients. This observation is suggestive for a different pathogenetic background in male and female patients.