Background: The imaging parameters that mandate further diagnostic workup in focal asymmetric breast densitiesare not clearly defined. To identify indications for further workup in Focal asymmetric breast densities (FABD)by doing ultrasonography.Methods: One-hundred women underwent breast ultrasonography after incidental discovery of FABD on mammograms.Mammograms and sonograms were evaluated for lesion location, associated calcifications, architecturaldistortion and change from previous examination when available.Results: Twenty three patients had abnormal sonographic findings and the site of sonographic abnormal findings was thesame as the site of FABD on mammography. Sonographic findings were 7 focal increases in fibrous tissue, 5 ductalectasias,4 simple cysts, complex cyst in one, 4 benign solid masses, one malignant solid mass and one with fibrous tissueat the site of pervious breast surgery. There was a significant relation between FABD in upper inner quadrant and normalsonography (p=0.036) and FABD in retroareolar region and ductal ectasia in sonography (p=0.002).Conclusion: FABD usually present a benign etiology and can safely be managed by follow up. Sonographyhelps the physician do tissue diagnosis by detecting mass with features of possibly malignancy, in the womenwith negative physical examination.