The aim of this work was to evaluate intracellular reactive oxygen species (ROS) levels, phosphatidylserine (PS) externalisation and mitochondrial membrane potential integrity in the spermatozoa of healthy donors and outpatients who consulted for infertility and to correlate the results with the classic sperm parameters. For the evaluation of intracellular ROS levels, PS externalisation and mitochondrial membrane potential integrity, the fluorescent compounds dihydroethidium, annexin V-FITC and JC-1, respectively, were used and analysed by using flow cytometry. Conventional seminal analysis, including motility, viability, morphology, sperm count and volume, was performed according to the WHO criteria. The mitochondrial membrane potential and ROS results showed significant differences between the spermatozoa of individuals with a normal semen analysis and those of the group presenting abnormality in at least one of the sperm parameters. Mitochondrial membrane potential showed a significant and direct correlation with all the sperm parameters analysed. ROS were inversely correlated with motility, viability and morphology. PS externalisation, however, did not show any differences between the two groups, nor was it correlated with the sperm parameters examined. The evaluation of mitochondrial membrane potential integrity is a test that reflects sperm quality, which makes it highly recommendable to be applied as a complement to routine sperm analyses.