In the first studies it has been revealed that combined influence of cytostatic cyclophosphamide and fragmented exogenous DNA preparation results in stable antitumor effect in mice.Moreover, the tumor growth is shown to be decreasing significantly if the animals are pre-treated with cyclophosphamide and DNA preparation and are immunized with tumor cells homogenate.The results obtained suppose that the antitumor effect observed is mediated by the activation of antigene-presenting dendritic cells resulting in the development of adaptive immunity.