The effect(s) of exercise on dietary protein requirements has (have) been a controversial topic for many years. Although most expert committees on nutrition have not provided an additional allowance of protein for active individuals, a considerable amount of experimental evidence has accumulated during the past 15 years which indicates that regular exercise does in fact increase protein needs. Part of the confusion is due to methodological difficulties and inadequate control of several interacting factors including: diet composition, total energy intake, exercise intensity, duration and training, ambient temperature, gender, and perhaps even age. Although definitive dietary recommendations for various athletic groups must await future study, the weight of current evidence suggests that strength or speed athletes should consume about 1.2-1.7 g protein/kg body weight.d-1 (approximately 100-212% of current recommendations) and endurance athletes about 1.2-1.4 g/kg.d-1 (approximately 100-175% of current recommendations). These quantities of protein can be obtained from a diet which consists of 12-15% energy from protein, unless total energy intake is insufficient. There is no evidence that protein intakes in this range will cause any adverse effects. Future studies with large sample sizes, adequate controls, and performance as well as physiological/biochemical measures are necessary to fine tune these recommendations.