Background: The present study evaluates the effects of energy drinks on the reproductive and biochemical parameters of adult male rats. Methods: A total of 40 male rats (Wistar) were exposed to an energy drink mixed with the drinking water for a period of 120 days. The animals were divided into four groups and exposed to increasing therapeutic doses (DT) of an energy drink, based on allometric extrapolation, resulting in values (mL/day) per animal of 250 g: DT1 2.36 mL, DT3 7.47 mL, and DT6 14.16 mL. The control group (CTRL) consumed water only. During the treatment, the rats were assessed for signs of toxicity. After treatment, the animals were sacrificed and their organs were weighed. Sperm parameters (motility, concentration, and morphology) were evaluated. The biochemical markers alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactic dehydrogenase, urea, creatinine, creatine phosphokinase, and creatine kinase MB fraction were measured, in addition to total cholesterol and testosterone. Results: There was a significant decrease (p < 0.05) in the concentration of sperm in the treated groups (DT1 8.5 ± 0.7; DT3 7.2 ± 0.9; DT6 8.4 ± 0.9) compared to the control group (12.3 ± 1.2). No difference was observed with respect to relative weights of the animals' organs, water consumption, signs of toxicity, behavioral changes, biochemical markers, and sperm motility and morphology. Conclusion: The long-term consumption of energy drinks interferes negatively with sperm concentration, without affecting sperm motility and morphology or altering the hepatic, cardiac, or renal functions.