The effects of the Chinese traditional drug, Rikkunshito (TJ-43) to adriamycin (ADM) -induced gastric cytotoxicity were studied histo-and cytochemically. Single i. p. injection of ADM (1.0mg/100g b. w.) to rats decreased cytochemical activities of cyto-chrome C oxidase (COX) in mitochondria and Ca²⁺-ATPase in plasma membrane of parietal cells. Oral administration of TJ-43 (100 mg/100g b. w.) to rats for 5 days prior to ADM injection almost completely prevented a decrease of both the enzyme activities by ADM. Post-treatment of TJ-43 after ADM injection showed lower intensities of both the enzyme activities than in normal rats, but significantly higher than those of ADM-injected rats without TJ-43 treatment. Localization of lysosomal acid phosphatase (AcPase) appeared to be confined to lysosomes in normal and TJ-43-pre-treated rat parietal cells, but the reaction products in the ADM-treated rat with and without TJ-43 post-treatment tended to disperse into the cytoplasm of most parietal cells. Therefore, a destructive effect of ADM on lysosomal membrane was suggested in ADM-injected rats with and without TJ-43 post-treatment. Taken together, TJ-43 appeared to have preventive effect against ADM-induced cytotoxicity, whereas its post-treatment had partial, but significant curative effects on the parietal cells.