In this study, the supplementary heat required when brooding turkey poults in winter and summer in the Kahramanmaras region of Turkey was determined using a heat and humidity balance method for a naturally ventilated house with a capacity of 6500 tom turkey poults. In the calculation of heat and humidity balance, temperature values, sensible heat and moisture production of tom turkey poults were taken from the American Society of Agricultural Engineers (ASAE) standards for corresponding turkey poult weights, and outside long term (1980 – 2005) monthly average temperatures were obtained from a local climate station. The coldest and warmest crucial months were determined as January (6.5 °C) and August (29.2 °C), respectively. When brooding was initiated in the first week of January, supplementary heat was needed for the subsequent five weeks, being 32937, 27028, 21721, 9476 and 5400 W per week, respectively. When brooding started in the first week of August, poults needed only 5544 W supplementary heat. However, tom turkey poults would nevertheless benefit from supplementary heat during this period because they are not yet fully feathered and the digestive system has not yet fully developed.