Abstract: In this study, cancer in mouse forestomach was induced by N-nitrososarcosine ethylester (NSEE),and effect of carboxyethylgermanium sesquioxide (Ge-132) on the carcinogenesis of squa-mous call carcinoma in mouse forestomach was investigated.玲sups showed that:(1)the occurrence of cancer in inthervening group was much lower than that in control group,(P<0.05),the inhibito-ry rate reached 42.900;(2) the intervening group contained less argyrophilic nucleolar organizer re-giong (Ag-NOR) than that of control group (P<0.05),and tiny, irregular Ag-NOR were more frequently seen in control group(P<0.05);(3)lymphocyte infiltrating response in intervening group was more obvious than that in control group (P<0.05).The results suggested that Ge-132 had in-hibitory effect on the occurrence of cancer in mouse forestomach;Ag-NOR stains showed that tom-pared with control group,the metabolic level and preliferative activity n intervening group was much lower,indicating that Ge-132 could block thd carcinogenesis of cancer in mouse forestomach, and, Ge-132 could increase the immunity of mice in intervening group,and this might be one of the machanisms of antitumor activity of Ge-132.