Four diets were formulated with potassium levels ranging from 0.4 to 1.0% and each diet was fed to laying hens at temperatures of 26.7%, 32.2, and 37.8 degrees C. Analyses for potassium in the plasma, egg, and excreta and potassium retained were used to determine the effects of heat stress on the potassium balance of laying hens. Urine potassium data from a surgically-altered hen provided insight into urinary excretion of potassium under conditions of heat stress. Regression analyses of the data obtained indicated that temperature significantly influenced plasma potassium concentrations, while egg and excreta potassium concentrations and the amount of potassium retained were not significantly influenced by temperature. The data suggest that 0.4% potassium in the diet is adequate for meeting potassium requirements under conditions of heat stress. However, 0.6% dietary potassium may be a more suitable level for assurance against a potassium imbalance at elevated temperatures. One percent dietary potassium appears to be an excessive level.