Day 7 bovine embryos, collected from superovulated donors, were frozen-thawed and those badly injured judging by morphological criteria were discarded. Then 127 of 153 embryos were transferred surgically to exactly synchronous recipients and to recipients +1 or −1 day out of phase. The highest pregnancy rate, 48%, was established after synchronous transfer. A marked drop in pregnancy (24.4%) resulted from the transfer of Day 7 embryos to Day 6 recipients. After transfer of Day 7 embryos to Day 8 recipients the pregnancy rate was still lower. It was concluded that freezing and thawing procedures to some extent decrease the capability of embryos to overcome the asynchrony and hence proper attention should be paid to the stage of the estrous cycle of the recipient relative to the age of the embryos.