Objective: This study was designed to investigate the combined effects of cadmium (Cd) and lead (Pb) on testosterone level in men. Design and Method: The heavy metal dataset of the Korean National Health and Nutrition Examination Survey (KNHANES) IV and V (2008 - 2012) was analyzed. Results: The serum testosterone level was significantly associated with the logtransformed blood Cd and Pb levels. For the highest quartile of Cd and Pb, the odds ratio (OR) of the risk of low serum testosterone level compared with the lowest quartile was 6.890 (Cd, 95% CI: 4.59-10.70) and 3.117 (Pb, 95% CI: 2.03-4.39) after adjusting for confounders (age, body mass index, smoking status, diabetes and alcohol intake), respectively. The adjusted OR of the risk of low serum testosterone level in the 4th quartile of both Cd and Pb was 13.7 (95% CI: 9.0-19.5) compared with the reference group (1st and 2nd quartile of Cd and Pb). Conclusions: This study is the most comprehensive investigation to date regarding the association between heavy metals and sex hormones in males.