Objective: This study aimed to evaluate outcomes, complications, and follow-up results of ultrasound-guided vacuum-assisted breast biopsy (UG-VABB) in BI-RADS 4 A and B lesions. Material and Methods: Between Agust 2014 to January 2018, fifty BI-RADS 4A and BI-RADS 4B lesions of 41 patients biopsied with 10G vacuum needle by a single radiologist were retrospectively evaluated. Results: All patients were females and mean age of the 41 patients was 50.12 ± 8.63. Of all lesions, 84% was benign, 6% was ADH, 4% was in-situ cancer, and 6% was diagnosed as malign. Follow-up duration after VABB was 0-51 months and mean was 20.92 months. Complications were as vasovagalinduced seizure in 3 patients (7.3%) and intramammary hematoma in 16 patients (39%). Hematoma was diagnosed in 3 patients (7.3%) at the 6 th month follow-up and it was resolved in all patients at the 12 th month follow-up. Higher breast density resulted in higher hematoma rates. There was no relationship between lesion BI-RADS subgroups, lesion size or sample number and hematoma development. During the follow-up, residue lesion in 1 (2.4%) patient and scar tissue in 2 (4.9%) patients was detected. Conclusion: US-guided VABB, with low complication rates and low scar development, is also a therapeutic excision method without remaining residue, which should be primarily preferred in smaller than 2 cm BI-RADS 4A and 4B lesions whose malignancy rates are relatively low. Hematoma, which is the most frequent complication, resorbed entirely in the 12 th month in all patients.