Pigs were exposed to prolonged chronic heat stress (HS) and thermoneutral (TN) conditions prenatally (during first of last half of gestation) or postnatally (7-10 wk starting at 14 wk of age). Gestational HS had minimal impact on carcass composition but may impact skeletal system structure and development. Additionally, results indicate that while similar levels of lean can be achieved in pigs subjected to chronic postnatal HS with increased time on feed, carcass fat may be decreased with HS.