This study was designed to describe the physiological, psychophysical, and psychological responses of firefighters to firefighting drills in a training structure containing live fires. Fifteen male firefighters, wearing standard turnout gear which resulted in full encapsulation, performed two firefighting tasks (advancing fire hose, chopping wood) while inside the training structure. Measurements of heart rate, tympanic membrane temperature, blood lactate, perceptions of respiration, mood, perceived exertion, and thermal sensation were obtained after 8 min of advancing fire hose, and again after 8 min of chopping. Heart rate and temperature increased significantly from baseline and from advancing hose to wood chopping, whereas blood lactate increased initially after advancing the hose and remained elevated at the end of the chopping task. At the completion of the test (both tasks), mean heart rate (182.3 b.min-1), temperature (40.1 degrees C, [104.1 degrees F]), and blood lactate (3.8 mMol) suggested that the firefighting tasks used in this study impose considerable physiological strain on firefighters. Psychophysical and psychological data mirrored the greater physiological strain following firefighting tasks performed in a hot environment while wearing full turnout gear.