Computer Aided Detection System for Microcalcifications in Digital Mammograms Hayat Mohamed1, Mai S. Mabrouk2*, Amr Sharawy3 1Biomedical Engineering, Cairo University, Giza, Egypt, yota_totos@hotmail.com msm_eng@yahoo.com2* Biomedical Engineering, MUST University, 6th of October, Egypt, 3 Biomedical Engineering, Cairo University, Giza, Egypt,amrarsha@gmail.com Abstract Breast cancer continues to be a significant public health problem in the world. Early detection is the key for improving breast cancer prognosis. Mammogram breast X-ray is considered the most reliable method in early detection of breast cancer. However, it is difficult for radiologists to provide both accurate and uniform evaluation for the enormous mammograms generated in widespread screening. Micro calcification clusters (MCCs) and masses are the two most important signs for the breast cancer, and their automated detection is very valuable for early breast cancer diagnosis. The main objective is to discuss the computer-aided detection system that has been proposed to assist the radiologists in detecting the specific abnormalities and improving the diagnostic accuracy in making the diagnostic decisions by applying techniques splits into three-steps procedure beginning with enhancement by using Histogram equalization(HE) and Morphological. Enhancement, followed by segmentation based on Otsu's threshold the region of interest for the identification of micro calcifications and mass lesions, and at last classification stage, which classify between normal and micro- calcifications 'patterns and then classify between benign and malignant micro- calcifications. In classification stage; three methods were used, the voting K-Nearest Neighbor classifier (K-NN)with prediction accuracy of 73%, Support Vector Machine classifier (SVM) with prediction accuracy of 83%, and Artificial Neural Network classifier(ANN) with prediction accuracy of 77%. Keywords: Micro calcifications (MCCs) Histogram equalization (HE), K-Nearest Neighbor classifier (K-NN), Support Vector Machine (SVM), Artificial Neural Network (ANN), Otsu's threshold.