The effect of zinc and histidine (a zinc chelator) on oxygen (O2) uptake by turkey sperm was examined in diluents without and with added fructose. The presence of .5 mM zinc in a diluent without fructose depressed sperm O2 uptake significantly below that of sperm in diluent alone or in diluent with 3 mM histidine but did not depress sperm fertility. Histidine had no effect on sperm O2 uptake. Sperm O2 uptake in diluents containing 1 mM fructose was significantly less in the presence of zinc than in diluents alone or in diluent with histidine. It was suggested that zinc may play a regulatory role in sperm O2 uptake in vivo.