Current ASAE standards of heat and moisture production are based primarily on data collected nearly four decades ago. Feedstuffs, swine practices, growth rate, and lean percentage have changed considerably in that time period and have a substantial effect on both heat and moisture production. In fact, recent research has shown that high-lean gain swine are more susceptible to high environmental temperatures – partially due to increased heat production. This increase in heat production cannot be met physiologically through increased sensible heat loss (i.e. surface area); therefore, latent heat loss must increase. Furthermore, synthetic amino acids can more closely match diet composition with swine nutrient requirements, and reduce heat production and nitrogen loss. This paper reviews the genetic, nutritional, and environmental effects on heat and moisture production of growing-finishing swine, and identifies the areas that need further investigation.