BACKGROUND Breast Ultrasound (US) is widely used as a diagnostic tool in evaluating mammographically detected masses,(1) palpable lumps,(2,3) nipple discharge(4) and in guiding percutaneous biopsy.(5) Breast ultrasound is a primary diagnostic tool along with mammography for the evaluation of breast masses. Aim-To determine the accuracy of Breast Ultrasound in evaluating BI-RADS 3 and 4 breast masses with pathologic diagnosis as reference gold standard. MATERIALS AND METHODS Study was conducted in the period, December 2015 to December 2016. A total of 756 patients who presented to the Surgery outpatient department with complaints of breast lump, pain or nipple discharge were subjected to breast imaging. From 756 patients, 143 patients who had BIRADS 3 and 4 mass were selected for the study. Patients with masses that fulfilled the BI-RADS 3 and 4 were enrolled in the study. Breast ultrasound with and without Doppler performed in these patients with GE Voluson S6 (Linear Array 4 - 12 MHz, Curved Array 2 - 8 MHz). Informed written consent for the ultrasound-guided biopsy procedures was obtained from each patient. RESULTS All the 143 breast masses were evaluated and categorised according to the BI-RADS classification on B mode US. A total of 51 masses were categorised into BI-RADS 3 and 92 masses into BI-RADS 4. Among the 51 BI-RADS category 3 masses, only 4 (7.8%) were malignant. Of the 92 masses of category 4, 75 (81.5%) were malignant on histopathology. Thus, the B mode US had a sensitivity of 94.9% and specificity of 73.4%, positive predictive value of 81.5% and negative predictive value of 92.2%; (P value < 0.001) in detecting malignancy. CONCLUSION Breast ultrasonography is an appropriate tool in the detection of cancer and should be included in the workup of symptomatic breast disease. Breast ultrasound has a very high sensitivity in detecting malignancies and guiding further management of the suspicious lesions. But the occurrence of false positive diagnosis in the clinical settings like that of inflammatory breast disease should also be considered and the management be decided after correlation with the clinical data and the biopsy results.