The aim of the present study was to examine the rate of activation and time-dependent changes in p34^cdc2 kinase and MAP kinase activities in porcine oocytes after injection of sperm extracts (SE) or treatment with Ca² ionophore to clarify whether SE injection is useful for porcine oocyte activation. SE was prepared from miniature pig sperm by non-ionic surfactant. Oocytes that were treated with Ca² ionophore and injected with SE were activated at rates of 41% and 46%, respectively. The activities of p34^cdc2 kinase and MAP kinase in each culture period (4, 8 and 12 h) in the Ca² ionophore group and SE injection group were significantly lower than those in the control group. These results suggest that SE injection induces decrease of p34^cdc2 kinase and MAP kinase activity, and induces oocyte activation, as well as Ca² ionophore treatment, but the induction was comparatively limited.