The effect of concentrations of copper (0.5, 1.5 mg l^-1), lead (10, 40, mg l^-1) and zinc (0.05 and 0.5 mgl^-1) singly or in combination on growth of Scenedesmus obliquus was studied. The results showed that there is a difference between the effects of each metal singly and in combinations with each others. Generally, heavy metals decreased the growth of Scenedesmus obliquus. High concentration of copper uptake exceeds its uptake in low concentration (58 and 42%, respectively). While the uptake of lead and zinc in low concentrations exceeds their uptake in high concentrations with percentages of (87%, 86%, 13% and 14%, respectively). Zinc uptake in combinations was dominant over the two other metals. The effect of heavy metals on ultrastructure of Scenedesmus obliquus by using the Transmission Electron Microscope was investigated.