OBJECTIVE To assess the accuracy and clinical usefulness of CT-guided core-needle biopsy in the diagnosis of omental pathology. METHODS We retrospectively reviewed the results of CT-guided percutaneous core biopsies in 25 patients with focal (n = 2) or diffuse (n = 23) omental pathology. These results were compared to the final diagnoses as determined by laparotomy (n = 15), laparoscopic biopsy (n = 3), endoscopic biopsy (n = 1), or by the results of percutaneous biopsy and clinical-radiological and bacteriological modalities (n = 6). The final diagnoses showed 4 patients with isolated omental pathology and 21 with widespread peritoneal involvement. The CT-guided biopsies were performed with 1.0-1.8-mm Surecut core-needles. RESULTS In 16 patients, the final diagnosis was metastatic adenocarcinoma--with the primary tumor sites in the ovary (n = 3), stomach (n = 1), appendix (n = 2), and unknown (n = 10). In the remaining 9 patients, the final diagnosis was hepatocellular carcinoma, lymphoma, and mesothelioma in 1 patient each; tuberculosis in 5; and actinomycosis in 1. Sufficient histological (n = 16) or cytological (n = 8) material was obtained by CT biopsy in 24/25 (96%) cases; the specimen was insufficient for diagnosis in 1 case. In differentiating benign from malignant disease, CT-guided biopsy showed a sensitivity, specificity and accuracy of respectively 89.5%, 100% and 92%. It gave a specific diagnosis in 78.9% (15/19) of patients with malignant conditions and in 50% (3/6) of patients with benign disorders. There were no biopsy-related complications. CONCLUSIONS CT-guided percutaneous core-needle biopsy of the omentum is a safe, useful and highly accurate procedure for diagnosing malignant omental pathology.