A significantly higher survival rate was obtained when frozen-thawed morulae were transferred to oviducts of recipients ovulating after donors rather than to those of synchronized or earlier ovulating recipients. The highest proportion of live young, 23%, was obtained after transfer of eggs to recipients ovulating 18 h after donors. The proportion of live young (48%) was significantly increased when frozen-thawed rabbit morulae were transferred into both oviducts of recipients at this stage.