To investigate the differences between male and female rats and the effects of sex hormones on tissue changes in the lung and liver in a sepsis model. Sixty Sprague-Dawley rats were divided into six groups of ten. Groups 1 and 2 were the control male and female groups, respectively, subjected only to sepsis; groups 3 and 4 were the male and female groups, respectively, subjected to sepsis, then given 0.04 mg/kg estrogen + progesterone (E-P) intramuscularly (i.m.); and groups 5 and 6 were the male and female groups, respectively, subjected to sepsis, then given 0.5 mg/kg testosterone (T) i.m. The rats were killed and the histopathological changes in the lung and liver were examined, and plasma endotoxin levels were measured. Histopathological examination revealed less congestion, portal inflammation, and focal necrosis of the liver, and less congestion, edema, and emphysematous and inflammatory changes in the lung in the E-P groups than in the other groups. Moreover, signs of systemic endotoxemia in plasma were proportionally less in the female rats and in the E-P groups than in the male rats and the T groups. Female rats subjected to sepsis showed less liver and lung tissue damage and less systemic endotoxemia than male rats, because of the effects of female sex hormones.