We report usefulness of ultrasound used as an adjunct diagnostic tool to mammogram in routine annual checkup for women breasts of certain ages and breast mass. The purpose of breast imaging is to detect areas of tissue distortion and breast cancers. A mammogram is the common diagnostic imaging modality used to find breast diseases but sometimes the mammogram might not give the doctor enough information especially in women with dense breasts. As a result, the patient may be asked to undergo ultrasound or magnetic resonance imaging as a better mean of judgment to the case. Because ultrasound is widely used, simple and safe to patients we were encouraged to emphasis on exploring its role adjunct to mammogram. A retrospective observation study was done at the diagnostic radiology department at King Abdulaziz University Hospital (KAUH) in the period from January 2012 to June 2012; we covered all women with dense breasts in mammography and ultrasound units. The study group was 40 patients. All patients were imaged with both mammography and ultrasound. The statistical measures of accuracy, sensitivity and specificity were calculated using the SPSS program. The results we obtained suggest that age and the physical density of breast potentially affect mammogram images of women with 41 years or smaller with sensitivity 66% and specificity 68%. Therefore, we recommend using ultrasound alongside the mammogram in women with dense breast for better diagnosis of small cancers that were not identified on mammography or clinical breast examination alone.