This study is a retrospective evaluation of the correlations between the presence and integrity of the capsule of nodular hepatocellular carcinomas (HCC) by dynamic CT and histopathology, with histopathologic evidence of tumor propagation to surrounding hepatic parenchyma. Dynamic CT scans of 75 nodular HCCs in 73 patients (61 men, 12 women; age range, 32-81; mean, 53) were evaluated regarding capsule visualization and integrity. Histopathologic findings of HCCs in resected specimens were correlated with the presence of a capsule, tumor invasion onto the capsule, and with the presence of microvascular emboli in the surrounding liver parenchyma. On histopathologic examination, capsules were present in 57 of 75 nodular HCCs; the capsules were invaded by tumor in 18 nodules and there were microvascular emboli around the nodular HCC in 49 cases. Capsule visualization by CT was correlated with the presence of capsule by histopathology (P<0.001). Disruption of capsule by CT was correlated with tumor invasion by histopathology (P=0.003) and with microvascular tumor emboli (P<0.001). The presence and structural integrity of HCC capsules on CT was closely correlated with the presence of capsule on histopathology and the absence of microvascular tumor emboli.