Prostasomes are vesicles present in human semen. They are secreted by the prostate and contain large amounts of cholesterol and sphingomyelin. Some of their proteins are enzymes. Prostasomes are involved in a number of biological functions. In previous papers we demonstrated that lipid can be transferred from prostasomes to sperm by a fusion process occurring at neutral or slightly acidic pH. In this paper we demonstrate that CD26/dipeptidyl peptidaseIV, an enzymatic activity absent in sperm, is transferred to sperm from prostasomes. This may be of particular interest since, by this procedure, sperm may acquire new membrane-bound enzymes and modify the catalytic activity of their surface.