Objective: To determine the normative cut-off score that defines hirsutism among Chinese women, and the effect of age, menstrual irregularities, and polycystic ovaries on the same. Design: Cross-sectional, population-based study. Setting: A multistage systematic cluster random sampling among 16 communities from two rural and two city regions. Patient(s): A representative sample of 2,988 women aged 20-45 years from the general population of Southern China. Intervention(s): Subjects underwent physical and ultrasound evaluations. Main Outcome Measure(s): Terminal hair growth was assessed using the modified Ferriman-Gallwey (mFG) scoring system. Result(s): An mFG score >= 5 was observed in 10% and a score of >= 2 in 25% of the subjects. Cluster analysis identified an mFG score of 5 as the cut-off value that defines abnormal terminal facial and body hair growth in a male pattern (i.e., hirsutism) in the total population; scores of 6, 5, and 4 for women aged 20-25, 26-30, and >30 years, respectively. Defined by these cut-off values, the prevalence of hirsutism in our total population was 10.5%; and decreased with increasing age: 14.4%, 10.7%, 7.9%, 3.6%, and 1.5%, respectively, in women aged 20-25, 26-30, 31-35, 36-40, and 41-45 years. Furthermore, the incidence of acne, menses irregularities, polycystic ovaries, and acanthosis nigricans were significantly increased among the hirsute women. Conclusion(s): An mFG score of 5 or greater indicates hair growth above the norm among women in the general Southern Chinese population, a cut-off value that decreases with increasing age. (Fertil Steril (R) 2011;96:792 6. (c) 2011 by American Society for Reproductive Medicine.)