Several studies have shown that the stomach has sufficient alcohol dehydrogenase (ADH) activity to metabolize some amount of orally administered alcohol and the sex-related differences in the first-pass metabolism of alcohol might be associated with differences in the activity of gastric ADH(GADH). The aim of this study was to asses the sex-related differences in GADH in 48 male and 48 female Sprague-Dawley rats aged 1, 4, 10, 15, 20, and 30 weeks which each aged group had same sex ratio. The GADH activity was determined spectrophotometrically at 37$^{circ}C$. The formation of NADH was monitored at 340nm for 10 minutes in the 1 ml of reaction mixture (0.5 M of Tris-HCl, pH 7.2 + 1.5 M of ethanol + 2.8 mM of NAD + 30 $mu$l gastric mucosal supernatant). The GADH activity (nM of NADH/min/mg of cytosolic protein) was calculated using molecular extinction coefficient of 6.22 $ extrm{cm}^2$/$mu$M for NADH. The GADH activities were 2.94$pm$0.82 (n=48) in female rats and 3.34$pm$2.17 (n=48) in male rats and had not significant difference between sex. However, the GADH activities were significantly (p<0.01) higher in female (1.91$pm$0.59 and 3.30$pm$0.49) than in male (0.68$pm$0.43 and 1.92$pm$0.81) of 1 and 4 weeks rats. However, it was significantly (p<0.05) higher in male (6.48$pm$1.81, 3.65$pm$1.04 and 5.13$pm$1.30) than in female (4.23$pm$1.23, 2.18$pm$0.77 and 2.56$pm$0.93) of 10, 20 and 30 weeks rats, respectively. Therefore, the results suggested that sex-related differences of the GADH activities in same aged rats were existed by age.