Abstract Objective: To evaluate the performance of USG guided core biopsy in suspicious breast lesions that is described as BI-RADS 4 in mammography & USG in correlation with histopathological findings. Method: This cross-sectional study was carried out in the Department of Radiology and Imaging, BSMMU, from January 2018 to December 2019. Patients, those who were advised for ultrasonography & mammography in department of Radiology & Imaging, sent from outdoor department of surgery and gynecology, BSMMU and diagnosed having BI-RADS 4 lesion, advised for biopsy. Result: In this study it was observed that among 100 cases of BI-RADS 4 lesions, 32(33%) were benign and 65(67%) lesions were malignant. Among malignant lesions (n=65), 4(6.2%) lesion were described as subcategory 4A by imaging, 19(29.2%) in 4B and 42(64.6%) as 4C. USG guided core biopsy was able to draw conclusive findings of histopathology in 97(97%) cases. Only 3(3%) cases were reported as doubtful findings and advised for re-biopsy. With no complication in majority cases (88, 88%) and minor complication in 12(12%) cases, USG guided core biopsy revealed 97% sensitivity. Conclusion: USG guided core biopsy is the effective diagnostic tool for suspicious breast lesions and percentage of malignant breast lesions within BI-RADS 4 subcategories in our population lies into BI-RADS 4 malignancy probability range.