The present of communication result of the analysis action urethane, that is yield of burning tobacco, provoked alterations on macrophages, complement system and red blood cells. Our data show that urethane high concentration kill macrophages and red blood cells and severely inhibits complement activity. These findings suggest that urethane high concentrations injury to macrophage's receptors, complement system and red blood cells and these are associated with pathologic process related with passively and actively smoking individuals.