Spermatozoa are transcriptionally silent cells that rely heavily on post-translational modifications to their existing protein complement in order to express the complex array of functional attributes needed to fertilize the oocyte. Post-translational changes are also involved in the aetiology of defective sperm function through the oxidative modification of proteins including the formation of adducts with cytotoxic aldehydes (malondialdehyde or 4-hydroxynonenal) generated as a result of lipid peroxidation. Spermatozoa are redox active cells that depend on the generation of reactive oxygen species (ROS) in order to achieve a state of capacitation; if ROS generation is suppressed, then sperm capacitation is impaired. However, the sustained generation of ROS can lead to a state of oxidative stress that results in the formation of lipid aldehydes that bind to key proteins within the mitochondrial electron transport chain (particularly succinic acid dehydrogenase) fueling yet more ROS generation in a self-perpetuating cycle that culminates in cell death. Such mitochondrial ROS generation is often associated with the entry of spermatozoa into the intrinsic apoptotic pathway which can be triggered when these cells are deprived of prosurvival factors needed to maintain PI3 kinase in an active phosphorylated state. A proteomic approach has been used to demonstrate that two such prosurvival factors are implicated in the maintenance of sperm function - insulin and prolactin. There are important implications in these results for the strategic management of sperm function in an applied context.