This paper presents some results on the irradiation of experimental animals with intertwined tumours by a low intensity laser radiation. In this study we used a He-Ne laser and a copper vapor laser. It was revealed in this study that radiation of a helium neon laser stimulates both the volume of tumour and the number of metastasis. On the other hand radiation of a copper vapor laser oppresses the growth of a turmour and shows a distinct antimetastasis action what prolongs the life of animals.