Background: Hypogonadism in men (total testosterone, < 350 ng/dL) is associated with higher risk of cardiovascular disease and mortality in men on dialysis therapy. We evaluated the association of hypogonadism with all-cause mortality in men with non-dialysis-dependent chronic kidney disease (CKD). Study Design: Retrospective, cohort study. Setting & Participants: 2,419 men with CKD stages 3-4 (estimated glomerular filtration rate, 15-59 mL/min/1.73 m(2)) who had total testosterone measured for cause between January 1, 2005, and October 31, 2011, at a tertiary-care center in Cleveland, OH. Predictors: Total testosterone measured using an immunoassay measurement in 3 forms: (1) categorized as low or testosterone replacement therapy versus normal, (2) continuous log testosterone, and (3) quintiles (100-226, 227-305, 306-392, 393-511, and 512-3,153 ng/dL). Outcomes: Factors associated with low total testosterone level and the association between low total testosterone level and all-cause mortality were evaluated using logistic regression, Cox proportional hazard models, and Kaplan-Meier survival curves. Results: Hypogonadism was found in 1,288 of 2,419 (53%) men. In a multivariable logistic regression analysis, African American ethnicity and higher estimated glomerular filtration rate were associated with lower odds of having hypogonadism. Diabetes and higher body mass index were associated with higher odds of having hypogonadism. 357 of 2,419 (15%) patients died during a median follow-up of 2.3 years. In the multivariate Cox model, testosterone level < 350 ng/dL or testosterone replacement therapy was not associated with mortality. In a multivariable model also adjusted for testosterone supplementation, higher log testosterone was associated with significantly lower mortality (HR per 1 log unit, 0.70; 95% CI, 0.55-0.89). When compared to the highest quintile, the second lowest quintile of testosterone was associated with higher mortality (HR, 1.53; 95% CI, 1.09-2.16). Limitations: Single-center study, timing of testosterone testing, lack of adjustment for proteinuria, and sampling bias. Conclusions: Low total testosterone level may be associated with higher mortality in men with CKD stages 3-4, but more studies are needed. (C) 2014 by the National Kidney Foundation, Inc.