1. The present study was aimed to investigate the effect of adding ascorbic acid or -lipoic acid to to the diet of broilers exposed to heat stress on performance and meat quality. 2. Heat stress caused a decrease in final body weight and feed consumption, whilst ascorbic acid (AA) and -lipoic acid (ALA) partly prevented the decrease in final body weight of males. 3. While heat stress increased the pH values of broiler drumsticks and breast meat, AA and ALA partly reduced this increase. For meat quality, AA and ALA reduced the adverse effects on the relative yellowness value, particularly on d 14 of storage. 4. It was determined that heat stress affected the microbiological quality of meat adversely, and that AA and ALA alleviated this effect to a certain extent. 5. In conclusion, while heat stress affected body weight gain and meat quality adversely, the supplementation of the ration with AA and ALA partly alleviated these adverse effects.