Melanoma is the most aggressive form of skin cancer, and the most rapidly expanding cancer in terms of worldwide incidence.Chemotherapeutic approaches to treat melanoma have been uniformly disappointing.Previous studies in mice have demonstrated that a high diluted complex derivate from natural compounds can stimulate the tumoricidal response by immunostimulation of macrophages and lymphocytes.Here we describe the in vivo regulation of B16F10 melanoma cells lung metastasis in C57BL/6 mice after inhalation treatment with a Chelidonium majus derivative complex (M1).Lungs were processed routinely for histological analysis, to detect and quantify perlecan by immunohistochemistry, for transmission electron microscopy analysis, and flow cytometry of blood and bone marrow markers.The results showed that M1 treatment inhibited metastasis grown in size and in number.It was observed difference in tumor nodules patterns distribution, concentration as well as in volume of tumor nodules.After M1 treatment, tumor nodules were small, fewer, and located predominantly in a peripheral distribution, while in control and vehicle groups the nodules size were larger and distributed throughout the lung.In both, blood and bone marrow cells, it was observed that blood marker parameters tended to be closest the control groups without tumors, specially granulocytes, CD11c+, and CD3+ cells.These results suggest that M 1 complex is a promising alternative approach to the complementary treatment of melanomas, a safety and without toxicity treatment, which may enhance the efficacy of conventional medicines by improving the immune response against tumor cells.