The prediction of the maximal heart rate in exercise testing usually is obtained from tables or regression equations that are derived from studies of large populations. Several of these studies have demonstrated that women will achieve a lower maximal heart rate when compared to men of the same age. We suggest the use of two equations that are specific for age and sex in order to facilitate the prediction of maximal heart rate. The equation for the prediction of the maximal heart rate for men is 205 - 1/2 age. The conventional formula (220 - age) should be used only to predict the maximal heart rate for women. The application and validity of these equations are examined and compared to the maximal heart rates of men and women reported from previous studies.