AbstractSurgical specimens from 75 patients with colorectal cancer were examined within 15 min of removal with a 7.5 MHz linear-array transducer. The echo pattern of 139 lymph nodes was analysed to evaluate previous criteria of malignancy and to establish other possible criteria, which could be testedin vivo. The pathologist examined each node without knowledge of the sonographic finding. Malignant nodes were larger than benign nodes. Of 21 nodes less than 5 mm in diameter, 20 were benign. Round nodes were malignant more often (45/78) than ovoid nodes (6/61). A homogeneous echo pattern was associated with malignancy in 39 of 82 nodes in contrast to 12 of 57 with a heterogeneous pattern. Thirty-one nodes were ovoid as well as heterogeneous and all of these were benign. A hyperechoic centre was found in 14 nodes of which two were malignant. The highest predictive value for malignancy (59%) was obtained by combining the discriminative properties of shape, homogeneity and echogenicity.Keywords: Colorectal carcinoma, Lymph nodes, Ultrasonography