Ejaculated spermatozoa, particularly in infertile men, have been shown to display morphological and biochemical features that are typical of an apoptotic phenotype in somatic cells. Deregulation of apoptosis is known to play roles in a number of disease processes, but roles for apoptosis in ejaculated spermatozoa and male infertility are poorly defined or have not been studied. Preliminary data demonstrated that populations of ejaculated spermatozoa express: (i) various degrees of plasma membrane translocation of phosphatidylserine and DNA fragmentation; and (ii) active caspase-3, the main executor of apoptosis in somatic cells, with an apparent exclusive cellular location to the mid-piece. Tests are currently being carried out on the effects of well-known apoptosis agonists and caspase inhibitors on such markers using purified populations of leukocyte-free ejaculated human spermatozoa. The main objective is to determine if somatic cell apoptosis markers are relevant indicators and/or causative factors of male infertility.