Objective: To determine the prevalence of elevated total and free T, and DHEAS, alone and in combination, in patients with polycystic ovary syndrome (PCOS). Design: Cross-sectional analysis. Setting: Tertiary care academic medical center. Patient(s): Seven hundred twenty patients diagnosed with PCOS according to the National Institutes of Health 1990 criteria. Intervention(s): History, physical examination, and blood sampling. Main Outcome Measure(s): Hyperandrogenemia, defined as at least one androgen value above the 95th percentile of 98 healthy control women (i.e., total T >88 ng/dL, free T >0.75 ng/dL, and DHEAS >2,750 ng/mL). Result(s): A total of 716 subjects with PCOS were included. The overall prevalence of hyperandrogenemia in PCOS was 75.3%. Supranormal levels of free T were present in 57.6%, of total T in 33.0%, and of DHEAS in 32.7% of patients with PCOS. When assessing the prevalence of two abnormal values, the prevalence of simultaneously elevated androgens was lowest with total T and DHEAS (1.7%) and highest with total T and free T (20.4%). Altogether, simultaneous elevations in all three markers were found in 8.7% of subjects with PCOS. Conclusion(s): Approximately three-fourths of patients with PCOS diagnosed by the National Institutes of Health 1990 criteria have evidence of hyperandrogenemia; the single most predictive assay was the measurement of free T with ∼60% of patients demonstrating supranormal levels. © 2010 American Society for Reproductive Medicine.