The experiments on inbred male rats have been carried out to estimate the effect of parenteral vinblastine, an inhibitor of catecholamine axoplasmatic transport, on gastric tumour growth induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) added to drinking water. The maximum tolerance dose of vinblastine was determined in subchronic experiments on 30 rats (0.25 mg/kg subcutaneously, once per week). Chronic experiments with combined introductions of MNNG and vinblastine were performed on 70 rats. Vinblastine was shown to inhibit carcinogenesis on "intestinization" stake and to decrease three-fold the incidence of gastric adenocarcinomas. Vinblastine-induced changes in the behaviour of animals reflect the decreased activity of central adrenergic processes. The role of catecholamines in the mechanisms of specific action of chemical carcinogens is discussed.