Background: To detect the accuracy of breast ultrasound in diagnosis of fibroadenoma and differentiate between typical and atypical ones. The impact of ultrasound criteria on patient management. (Biopsy versus follow up). A prospective study were done to 71 patients. Diagnosis was reached either by performing follow up study or after revision of core biopsy/surgical specimens. Results: In our study, we had 35 ultrasound detected atypical fibroadenoma, seven out of the 35 (20 %) proven to be complex fibroadenoma by pathology while in another 20 patients, 36 fibroadenomas with typical criteria were detected by both ultrasound and regular follow up. The most ultrasound features which showed statistical significance were the posterior shadowing feature (100% atypical versus 25% typical with significant p value < 0.01), and vessel arrangement (85.7% versus 0% have central arrangement with significant p value < 0.01) helped to differentiate between simple and complex ones. We calculate the sensitivity, specificity, PPV, and NPV to be 100%, 74%, 46%, and 100%. Conclusion: Arrangement of vessels and posterior features are the most important criteria to differentiate simple and complex FAD.