Abstract: Using a fractat model, we give a new interpretation of the reversed sigmoidal curves of fracture surface profile length obtained in some experiments. It is pointed out that a single parameter (fractal dimension D) is not sufficient to characterize a fractal curve completely. It is shown that the initiator length L0 is also important to characterize a fractal curve. We have derived a formula which correlate the fracture energy with the fractal parameters of the fracture surfaces and analyzed some experimental data.