Mass in the Right Iliac Fossa (RIF) is clinically difficult to differentiate, ultrasonography a quick non-invasive investigation has bridged the gap between clinical examination and direct visualization. The study was done to know the efficacy of ultrasonography in pre operative evaluation of RIF mass. MATERIALS AND METHODS: The data for this prospective study was obtained from 300 patients admitted/ attending OPD with a clinical diagnosis of RIF mass. Ultrasonography was done and a provisional diagnosis was obtained. The final diagnosis was obtained with histopathological examination[HPE] or by other standard methods. The sonological diagnosis was compared with final diagnosis. RESULTS: Out of 300 patients studied 236 were operable. Ultrasonography was able to diagnose 228 out of the 236 (Sensitivity of 96.7%) as operable cases and the remaining eight were inconclusive report. Ultrasonography was able to rule out all non operable cases with 100% specificity. The final diagnosis correlated with sonological diagnosis in 284 cases with sensitivity of 94.6% while clinical diagnosis correlated with final diagnosis in 232 cases with sensitivity of 77.3%.The most common conditions being appendicular mass followed by appendicular abscess and ileocaecal TB. DISCUSSION: Thus ultrasonography in experienced hands is an invaluable tool for preoperative evaluation of RIF mass. It has favorable sensitivity and specificity in differentiating RIF mass and 100% sensitivity and specificity in detecting cases which needs emergency intervention. In countries like India where other radiological investigation modalities are present only in higher center, ultrasonography becomes an invaluable tool in diagnosis and evaluation of RIF mass for practitioners in semi-urban and rural settings.