Aim: Firefighters experience short bursts of extreme physical and psychological stress punctuating long periods of tedium. For short intervals, the physical demands of firefighting may approach the limits of human capacity, so there is a need to find the most appropriate type of exercise training that achieve the best cardiopulmonary fitness in firefighters that enables them to do their work. The purpose of this study was to determine changes in cardiopulmonary fitness after aerobic and anaerobic exercise training in firefighters. Method: Forty firefighter workers who practiced their job for no less than fifteen years were enrolled in this study, their age ranged from 32 to 41 years. Participants were included into 2 equal groups; group (A) received aerobic treadmill walking exercise training for 3 months, at a frequency of 4 sessions per week. The second group (B) received anaerobic exercise training for 3 months, at a frequency of 2 sessions per week. Measurements of systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), minute ventilation (VE) and Maximum oxygen consumption (VO2max) obtained for both groups before and after the exercise program. Result: The mean SBP, DBP and HR values were significantly decreased, where the mean VE and VO2max values were significantly increased in group (A) after training. The mean SBP, DBP and HR values were not significant statistically and the mean VE and VO2max values were significantly increased in group (B) after training. There were significant differences between mean levels of SBP, DBP ,HR and VE in group (A) and group (B) after training, where there was no significant difference between mean levels of VO2max in group (A) and group (B) after training. Conclusion: Aerobic exercise training is the most appropriate type of exercise training that achieves the best cardiopulmonary fitness in firefighters that enables them to do their work.