Research question: Is the sole measurement of total testosterone sufficient to assess the presence of hyperandrogenism in women with polycystic ovary syndrome (PCOS)? Design: Serum samples from 294 patients with PCOS who met the Rotterdam criteria were used for the analysis of total testosterone by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) and chemiluminescent immunoassay (CLIA). The free androgen index (FAI) was calculated as total testosterone (TT)/sex hormone-binding globulin (SHBG) × 100%, and the presence/degree of hirsutism were assessed using the modified and simplified Ferriman–Gallwey (mFG and sFG, respectively) scoring systems. Results: The hirsute subjects presented higher LC-MS/MS-based total testosterone and FAI values than the non-hirsute subjects (all P < 0.001), including those defined based on mFG ≥5 or sFG ≥3. Total testosterone and FAI were both positively correlated with the mFG (rank correlation coefficient [RCC] 0.598 and 0.443, P < 0.001) or sFG (RCC 0.747 and 0.568, P < 0.001) score, and a receiver operating characteristic curve analysis indicated that both parameters could significantly predict the presence of hirsutism determined by the mFG (area under the curve [AUC] 0.797 and 0.725, P < 0.001) or sFG (AUC 0.894 and 0.817, P < 0.001) score. However, similar results were not obtained with the CLIA platform. Conclusions: In this East Asian population, total testosterone was found to be a strong predictor of the presence and degree of hyperandrogenism (i.e. assessed by the presence and degree of hirsutism), but this finding was obtained only if the total testosterone level was measured by LC-MS/MS and not by CLIA. These findings might have important implications for global epidemiologic, phenotypic and clinical studies of PCOS.