Background. Although many arguments have been raised on the role of heredity in the etiology of acne, the relevant genetic elements in the pathogenesis of the disease are not well established. Objective: The aim of our study was to evaluate the association between a genetic polymorphism in the promoter region of the CYP17 gene and the development of acne. Methods: 206 acne patients and 200 controls were included in the study. A polymerase chain reaction (PCR) sequencing technique was used to reveal a CYP17 gene polymorphism in its promoter region. A X-2 test was used for data analysis. Results:CYP17 -34T/C polymorphism was found and the frequency distribution of the C/C homozygotes and C allele in the male patients with severe acne (33.3 and 60.9%, respectively) were statistically significantly different from those of the control samples (18.2 and 46.6%; p < 0.05). No significant difference was observed between the female patients, mild + moderate male patients and their controls, respectively. Conclusion: The CYP17 -34C/C homozygote Chinese men are at a significantly increased risk of developing severe acne. Copyright (c) 2006 S. Karger AG, Basel.