A novel approach to mammographic image segmentation, termed as PCNN-based level set algorithm, is presented in this paper. As well known, it is difficult to robustly achieve mammogram image segmentation due to low contrast between normal and lesion tissues. Therefore, Pulse Coupled Neural Network (PCNN) algorithm is firstly employed to achieve mammary-specific and mass edge detection for subsequently extracting contour as the initial zero level set. The proposed scheme accurately obtains the initial contour for level set evolution, which does not suffer from the drawback that level set method is sensitive to the initial contour. Especially, an improved level set evolution is performed to segment the images and get the final results. A preliminary evaluation of the proposed method performs on a known public database, namely MIAS, which demonstrates that the proposed framework in this paper can potentially obtain better masses detection results than traditional CV and VFC model in terms of accuracy.