The fractal analysis is most usefulincharacterizing the structure of branching trees, root of plants, leaves, membrane surface of cells and so on. The fundamental underlying principle in fractal geometry is self-similarity and scale invariance which is a principle in the development and growth of biological forms. The exponent of these properties is the fractal dimension which is direct measure of the relative degree of complexity of the figure. In this work we determined the fractal dimension of the tomato plants treated with zinc and cadmium. Our results showed that the fractal structure tomato leaves changed after the treatment with these heavy metals by comparison with the control ones.