Turner's syndrome (TS) is a genetic disorder caused by numeric and/or structural abnormalities of the X chromosome; it is characterized by short stature, gonadal dysgenesis, and frequently by webbed neck, cubitus valgus, and lymphedema at birth. TS has been associated with several cutaneous abnormalities including an increased frequency of pigmented nevi, but few reports consider nevi in detail. Halo nevus (HN) is clinically defined as a melanocytic nevus surrounded by a halo of depigmentation. Vitiligo, a dermatologic disorder characterized by the presence of depigmented patches on the skin, has been described in the list of cutaneous findings associated with TS. The aim of this study was to determine the prevalence of HN and vitiligo in TS and to evaluate if a correlation between major histocompatibility complex genes, karyotype, autoimmunity, therapies, and the presence of HN exists. Of the 72 patients with TS examined, 13 had HN, a prevalence of 18.05%, which was significantly higher than in our control group (1%; P=.000001). On the contrary, only 2 patients with TS (2.77%, P=not significant) had vitiligo. By comparing the distribution of HLA class I alleles between patients with TS who did (13 of 72) and did not (59 of 72) have HN, we observed a significantly higher frequency of HLA-Cw6 in patients with TS and HN than in those without HN (26.92% vs 6.78%, respectively; P=.0067; odds ratio=5.06). The study of HLA class II genomic polymorphisms showed that the DRB1(*)0701 and DQB1*02 alleles for patients with TS and HN were overrepresented when compared with those without HN (34.61% vs 11.86%, respectively, P=.0078, odds ratio=3.93; and 34.61% vs 19.49%, respectively, P=.1386, odds ratio=2.19). In conclusion, this study is the first to demonstrate an increased prevalence of HN for patients with TS. Furthermore, the data suggest that a HN putative susceptibility gene in TS is located close to the HLA-C locus.