Tunnel ventilation has been adopted as an effective approach to combatting heat stress in poultry. Setting tunnel air velocity to levels that ensure bird comfort, while optimizing performance is an important goal. In recent years, biotelemetry has provided a way to effectively evaluate the impact of management practices on poultry physiology. In this study, we present an approach for evaluating the effects of heat stress and tunnel ventilation on poultry deep body temperature (DBT) using biotelemetry. Three consecutive experiments were conducted using 6 broilers, each at the ages of 8.6, 9.0, and 9.4 wk. Experiments spanned approximately 12 h each and led to 18 data sets. DBT responses of birds under no ventilation rose by as much as 3°C as a result of step increases in ambient temperature. Birds exposed to tunnel ventilation maintained a lower DBT by as much as 0.9°C. During experiment days, birds exposed to tunnel ventilation consistently gained weight with a percentage weight gain ranging from 1% to 11%. Birds not exposed to tunnel ventilation behaved less consistently with some gaining as much as 14% while others lost as much as 9%. Although further studies are required to derive more comprehensive and more statistically significant results, this study provided preliminary data that is needed to warrant such studies, and a stepping stone for making optimal management and risk assessment decisions that are based on physiological needs of the birds.