Effects of oral administration of melengestrol acetate on estrus synchronization and conception were investigated in 24 Holstein heifers. In addition, effects of feeding melengestrol acetate starting at 90 days postconception through 30 days postpartum on growth, gestation length, birth weight, and lactation were studied.Daily feeding of 1mg of melengestrol acetate to heifers for 14 consecutive days irrespective of stage of estrous cycle inhibited estrus during treatment and synchronized estrus following withdrawal. Treatment lowered (P<.05) conception at first post-treatment estrus. No difference in conception was observed between single and double inseminations. Services per conception for the treated animals were higher (P<.05) than controls (2.64 versus 1.54). Postconception feeding of melengestrol acetate resulted in no differences (P>.05) in weight gain, gestation length, or calf birth weight. There were no differences (P>.05) in lactation length, milk and fat production during post-treatment lactation.