Abstract: In this study, the effect of different ovulation status on pregnancy rates in surrogate recipient gilts receiving somatic nuclear transfer embryos was evaluated, in order to determine the optimal stage of the estrus cycle to achieve the highest pregnancy rates. Porcine somatic cell cloned embryos on 2 d in vitro were transplanted into the 12 d estrous recipient gilts. Recipient gilts were divided into two categories according to follicular development and ovulation status: just prior to ovulation or ovulating (Group 1); perovulation or after ovulation（Group 2）. The results were as follows：(1) pregnancy rate on 30 d of six recipient gilts from Group 1 was 100%; and the pregnancy rate on 30 d of ten recipient gilts from Group 2 was 40%, the data significantly different between Group 1 and Group 2 (P<0.05); (2) For the fullterm pregnancy rate of recipient gilts, extremely significant difference was observed between Group 1 and Group 2 (100% vs. 20%, P<0.01). These results suggested that development stage of porcine somatic cloning embryos on 2 d in vitro with recipient gilt′s womb environment of ovulation status of just prior to ovulation or ovulating was the best in the same period. It may achieve the best efficiency of embryo transfer.