Involvement of the peritoneum, omentum, and mesentery can be due to primary and secondary neoplastic and non neoplastic conditions. Differentiation of neoplastic involvement of the omentum from benign causes of omental thickening can be a challenge in the clinical practice. Ultrasound allows the detection and characterization of such lesions. Pulsed and color Doppler sonography have been used with the attempt to differentiate benign from malignant tumors of various origin by assessing tumor neovascularity.Image-guided peritoneal and omental core biopsy can be safely done for determining the tumor type.