To investigate sex differences in the effect of a military field exercise on physical performance, body composition, and blood biomarkers. Measurements were done in 23 male and 12 female conscripts before, and 0, 1, 3, 7, and 14days after a 6-day military field exercise. During the field exercise, body mass decreased more in men (-6.5±1.1kg) than in women (-2.7±0.7kg), and muscle mass decreased only in men (-2.7±1.0kg). Body composition recovered within one week. Performance decreased, with no differences between men and women for countermovement jump (CMJ,-19±8 vs. -18±11%), medicine ball throw (MBT, -11±7 vs. -11±7%), and an anaerobic performance test (EVAC, -55±22 vs. -47±31%, men and women, respectively). MBT and EVAC performance recovered within two weeks, whereas CMJ performance was still reduced in men (-17±6%) and women (-9±8%) after two weeks recovery, with a larger reduction in men. Both men and women decreased [IGF-1] (-28±9 vs. -41±8%) and increased [cortisol] (26±26 vs. 66±93%, men and women, respectively) during the exercise. Most biomarkers returned to baseline values within one week. Men lost more body mass and muscle mass than women during a field exercise, but these differences did not lead to sex differences in changes in explosive strength and anaerobic performance. However, women recovered explosive strength in the legs faster than men.