Twelve fall-lambing lactating, Rambouillet ewes were laparotimized shortly after the end of the first lactation estrus, and all had a corpus luteum from previous ovulation as well as a newly formed corpus hemorrhagicum. Another group of 40 ewes was checked twice daily for estrus beginning the day after lambing, and smears of cervical mucus were made on alternate days. At the time of appearance of the fern-like pattern that is typical of estrus in cycling ewes, none of these lactating ewes would accept the ram and none showed any other symptoms of heat. Eight of these ewes were laparotomized the day after the first appearance of the fern pattern, and all had recently ovulated as shown by newly formed corpora hemorrhagica. Positive smears accompanied by estrus occurred in 39 of the 40 ewes between 16 and 19 days after the first estrual smear. In another study 20 ewes were forcemated when the fern pattern first occurred after lambing. Only one ewe lambed to this breeding.