To determine the clinical outcome of breast cancer BI-RADS 4 lesions and seek a more effective managementguideline, we conducted a retrospective study of all BI-RADS4 patients diagnosed between 2003-2008 with followup time not less than 2 years. A total of 392 cases of BI-RADS 4 were identified and 320 could be sub-categorisedas 4a, 4b and 4c. Overall malignant positive results were 7.65, 38.7 and 58.percent, respectively. In all casesassigned to the close follow up group, no malignancy was detectable (P<0.02). The results of the study suggestedthat BI-RADS sub-categories have benefit for cancer diagnosis and treatment decisions of clinicians and it mightbe possible to set up a safe follow-up guideline in selected groups of patients to minimize un-necessary tissuebiopsy for breast cancer detection.