Histopathological study has been carried out to elucidate the protective effect of Korean red ginseng water extract (KRG-WE) on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced acute toxicity in male guinea pigs. Forty male guinea pigs ($200{pm}20g$) were divided into 4 groups: normal controls (group 1) received vehicle and saline; group 2 (single TCDD-treated) received TCDD (5 ${mu}g/kg$, single dose) and saline; group 3 received KRG-WE (200 mg/kg, i.p.) for 2 weeks starting 1 week before TCDD-exposure; group 4 received same dose of KRG-WE for 7 days from the day of TCDD-exposure. Weights of liver, testis, kidney, spleen and lung of the TCDD-exposed guinea pigs were significantly decreased. Thymus was severely shrunken, thereby could not be distinguished from adipose tissue in group 2 animals. Focal interstitial inflammation and fibrosis were observed from the lung parenchyma of group 2 animals. Furthermore, moderate swelling of hepatocyte, diffused aggregates of hemosiderin-laden macrophages from the Prussian blue stained spleen, marked decrease in spermatogenesis, and pyknotic and degenerative changes in the renal tubules were observed from intestinal organs of group 2 animals. On the other hand, histopathological damage was moderately to markedly alleviated in groups 3 and 4, but pretreatment of KRG-WE was more effective than the simultaneous treatment. In particular, TCDD-induced testicular atrophy was significantly attenuated by KRG-WE (p<0.01). From these results, it could be suggested that Korean red ginseng might be a useful herb that prevented TCDD-induced toxicity on liver, testis, kidney and spleen.