Lead is highly toxic and persistent in the environment and, thus, a major concern for public health. In this study, the effects of lead chloride (PbCl₂) on mouse epididymal sperm were evaluated. Male mice were subcutaneously injected with 74 and 100 mg PbCl₂/kg body weight for four consecutive days. Sperm was collected from the epididymis and several parameters of sperm function, such as sperm density, motility, viability, mitochondrial function, acrosome integrity and morphology, were evaluated. Furthermore, DNA fragmentation was assessed by the terminal deoxylnucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick-end labelling (TUNEL) assay and chromatin integrity was evaluated by sperm chromatin structure assay (SCSA). In order to assess direct effects on existing sperm population, we sacrificed one group for each condition at day 5. The effects of lead upon one entire spermatogenic cycle were evaluated on day 35. Both lead concentrations used in this work affected sperm motility, although no significant differences were observed in sperm viability, mitochondrial function and DNA/chromatin integrity. However, a decrease in the percentage of intact acrosomes was also observed, mirroring a lead-induced premature acrosome reaction. Thus, the results obtained indicate that, together with impaired motility, the effect of lead toxicity on acrosome integrity, leading to premature reaction, may compromise the ability of sperm to fertilize the oocyte.