Recent evidence has shown the important role of macrophages in both tumor development and progression. To investigate the role of macrophages we used a mouse model known as MaFIA (Macrophage Fas Induced Apoptosis) mice that allows for the selective deletion of macrophages. Mice were given melanoma cells at various stages of depletion. Tumor mass was measured and organs were processed for flow cytometry to measure melanoma cell migration. The results show that mice receiving depletion treatment have larger tumor sizes and weights than those mice retaining their macrophage population. We detect metastasis in both the lung and kidney in both macrophage depleted and non depleted mice. The more macrophages in an organ the larger the amount of melanoma positive cells are detected.