Effects of culture medium energy and protein source on in vitro maturation of cumulus-intact procine oocytes were examined. The bicarbonate buffered Whittens medium was superior to the PB1 medium buffered with phosphate salts in supporting in vitro maturation. However, modification of energy source of the PB1 medium by reducing Na-pyruvate concentration and adding lactate salts gave also high maturation rate. The supplementation of Whittens medium with 1 g and 3 g BSA/l as a protein source significantly increased incidence of maturation and improved handling of oocytes. There was no significant difference in the ability of low concentration (1 g/l) and high concentration (3 g/l) of BSA in culture medium to support maturation.