Testosterone (T) administration (TA) increases serum T and lean body mass (LBM). Although TA-mediated increases LBM may enhance physical performance, the data are largely equivocal, which may be due to differences study populations, the magnitude change in serum T and LBM, or the performance metrics themselves. PURPOSE: This meta-analysis explored the effects of TA on changes in serum T, LBM, and physical performance. The association between increases in serum T and LBM was assessed, and if changes in LBM, study population, or the performance metrics studied affected physical performance was determined. METHODS: A systematic review of double-blind randomized control/clinical trials comparing TA versus placebo on serum T, LBM, and physical performance was performed. Data were extracted from 20 eligible manuscripts. Effect sizes (ES) were assessed using Hedge’s g and a random effects model. Data are presented as ES (95% CI). RESULTS: Compared to placebo, TA had a large effect on serum T [2.65 (1.35, 3.96), p < 0.001], a small effect on LBM [0.32 (0.18, 0.46), p < 0.001], and a trivial effect on overall performance [0.14 (0.08, 0.20), p < 0.001]. Changes in serum T in TA groups were not associated with the ES of TA on LBM compared to placebo (p = 0.221). However, when TA groups were dichotomized based on median increase in serum T, medium [0.50 (0.23, 0.76), p < 0.05] and small [0.22 (0.14, 0.29), p < 0.05] effects were observed for LBM in those with increases in serum T above and below 8.82 nmol/L, respectively. Overall, performance increased with TA in diseased [0.17 (0.06, 0.27), p < 0.05] and older (60+ years) [0.16 (0.08, 0.24), p < 0.05] males, but not in younger (18-55 years) males. TA increased lower body [0.09 (0.04, 0.14), p < 0.05], upper body [0.22 (0.03, 0.41), p < 0.05], and handgrip [0.14 (0.06, 0.22), p < 0.05] strength, and lower body muscular endurance [0.38 (0.09, 0.68), p < 0.05]. TA had no effect on lower body power, aerobic endurance, and functional performance. CONCLUSIONS: These data show that the effects of TA on: 1) LBM are mediated by the overall effect of TA on serum T concentrations, and 2) physical performance are observed in mainly tests of muscular strength and endurance in diseased and older males.