1. The vertical temperature profile in a broiler house depends on several factors: ground temperature, heat production by the birds, heating of litter by resting birds, stratification and radiation, microbial heat production in the litter, moisture loss from litter and natural convection around the birds. The effect on the vertical temperature profile is calculated for each factor and the effects are finally combined to estimate vertical temperature distribution. 2. The vertical temperature profile in a commercial broiler house depends on the age of the birds. Influential factors for young broilers are ground temperature and stratification. For older broilers, influential factors are floor construction and ground-water table, heat production of broilers and litter, the behaviour of the broilers and air circulation in the house. 3. Temperatures in the living zone can differ appreciably, by a maximum of about 4 degrees C, from mean house temperature. 4. The velocity of air induced by the heat production of the broilers is about 5 cm/s. This provides good air mixing in the living zone.