Breast Cancer is one of the major causes of death among women. Early diagnosis can improve the patient's survival rate. Traditional diagnosis method such as biopsy is not much efficient. However due to the large scale of the medical image data, Inspired by the advanced computing technology which is capable of performing image processing using computer aided diagnosis (CAD) systems to assist clinicians detect forms of cancer. Preprocessing is the basic step in mammogram processing to remove the noise effects. This paper reviews fully automated de-noising techniques such as median, Gaussian, wiener, guided, hybrid median filters are de-noising filters, used to remove noise from a mammogram image. PSNR and MSE measurement and Analysis is done for evaluating the performance of the filter.