The present study was undertaken to evaluate the acute effect of prior resistance training of varying intensities on energy expenditure and substrate utilization during subsequent aerobic exercise. Eleven males and 21 females completed three experimental trials consisting of (1) aerobic exercise only (C), (2) aerobic exercise preceded by a high-intensity resistance training (HI), and (3) aerobic exercise preceded by a low-intensity resistance training (LO). Resistance training produced an equal volume between HI and LO and consisted of six exercises with each performed for three sets of eight repetitions at 90% of 8-RM in HI and three sets of 12 repetitions at 60% of 8-RM in LO. Aerobic exercise was performed on a cycle ergometer at 50% VO(2)peak for 20 min in all trials. Oxygen uptake (VO2), and carbohydrate and fat oxidation were determined throughout each aerobic exercise session. Fat oxidation rate was higher (P < 0.05) in HI than either LO or C in both males and females. VO2 was also higher (P < 0.05) in HI than either LO or C in females. In males, although between-trial differences in VO2 did not reach statistical significance, they were consistent with the trend seen in females. No differences in carbohydrate oxidation rates were observed across the three trials in either gender group. It appears that in training that combines both aerobic and resistance exercises, performing a comparatively higher intensity resistance exercise first would augment fat utilization and energy expenditure during subsequent aerobic exercise.