An experiment is described in which three diets differing in protein and energy content but having a constant energy:protein ratio, were each fed to three groups of broiler chickens to four weeks of age. The three groups on each diet were fed ad lib., for 12 h continuously followed by a 12 h fasting period each day. or for repetitive 6 h feeding and fasting periods. Lighting was supplied for 24 h/d. Broilers fed ad lib had in all cases a significantly greater body mass and consumed significantly more of each diet than those fed the corresponding diet for 12 h/d. The high protein diet proved superior to the other diets in promoting growth and food consumption, although when fed ad lib the cost per kg gain in body mass was greater for this diet than for the low protein diet. The converse was found when broilers were fed continuously for 12 h/d. There appears to be a definite advantage in feeding a high protein. high energy diet under conditions where broilers do not have access to food for 24 h/d during the first four weeks of age, and also if a maximum number of batches of broilers are to be reared in a broiler house each year.