Introduction: We want to evaluate the sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of BI-RADS ultrasound, as well as PPV and NPV of BI-RADS ultrasound lexicon. Methods: A total of 517 ultrasound-guided breast biopsy cases were performed within three years. A total of 324 cases remained after 193 cases were excluded from this study. The sensitivity, specificity, accuracy, PPV and NPV of overall BI-RADS and PPV for each BI-RADS categories were calculated from the data when compared with histopathological examination (HPE) finding. One observer evaluated four criteria of BI-RADS ultrasound lexicon; margin, echogenicity, posterior artefact and internal echo from static sonographic images to determine the PPV and NPV of sonographic BI-RADS lexicon based on HPE correlation. Results: There were 236 (72.8%) benign and 88 (27.1%) malignant lesions. The overall BI-RADS has a sensitivity of 93.18%, specificity of 66.95%, accuracy of 74.07% with PPV and NPV of 51.25% and 96.34% respectively. The PPV of each BI-RADS categories were; BI-RADS 2 (9.09%), BI-RADS 3 (3.27%), BI-RADS 4 (39.02%) and BI-RADS 5 (91.89%). The highest predictive value for malignancy was irregular margin (52.3%) and for benign was well-defined margin (89.7%). Criteria for margin and posterior artefact had a significant association with HPE (p<0.0001) in differentiating between malignant and benign breast lesions in breast ultrasound. Conclusion: Overlapping benign and malignant sonographic breast lesion descriptors tend to influence radiologist’s decision to overcall final BI-RADS categories. The margin and posterior artefact are the important criteria in BI-RADS lexicon in differentiating benign and malignant breast lesion.