To analyze the expression and distribution of cannabinoid receptors in human sperm cells and evaluate the effects of activation of receptors by specific agonists and antagonists, with a special emphasis on the CB(2) receptor.We performed expression assays for CB(1) and CB(2) by reverse transcriptase PCR, Western blot, and immunofluorescence techniques in spermatozoa and performed motility analysis after incubation of semen samples with cannabinoid agonists and CB(2) antagonist SR144528.Academic research laboratory.Semen from 50 normozoospermic, healthy human donors.Spermatozoa isolated from semen by two consecutive swim-ups were used for all techniques.Reverse transcriptase PCR amplification gels, immunoblots, indirect immunofluorescence antibody assays, and percentage of motile sperm.We have verified the presence of CB(1) and CB(2) receptors in human spermatozoa. The distribution of both of these receptors was distinct. Incubation with selective cannabinoid receptor agonists induced a significant reduction in the proportion of rapidly progressive motile spermatozoa, and whereas the CB(1) agonist increased the proportion of immobile sperm cells, the CB(2) receptor agonist increased the slow/sluggish progressive sperm cell population. The effect of the CB(2) agonist was antagonized by the CB(2)-specific antagonist.The functional CB(2) cannabinoid receptor is present in human spermatozoa and regulates the sperm motility in a more distinct manner than CB(1).