Timed artificial insemination (AI) programs are commonly used in the dairy industry for lactating cows, but less so in replacement heifers. Excellent programs using combinations of prostaglandin F_2α and gonadotropin-releasing hormone in protocols relying on timed AI without detection of estrus or in protocols that combine timed AI with inseminations performed after detected estrus are able to achieve acceptable pregnancy percentages. In herds with excellent estrus detection, timed AI programs serve as a failsafe system to address cows or heifers not yet inseminated after a defined period of estrus detection.