The patient was a 77-year-old man with a 4.0 cm hepatictumor in hepaticsegment 4. Plain computed tomography(CT) showed the tumor with low density. On dynamicexamination, the tumor showed heterogeneous enhancement during the arterial phase. Magneticresonanc e imaging showed the tumor as a low intensity area in the hepatobiliary phase in hepatic segments 4, 6, and 8. A month later, CT showed an enlarged tumor in segment 4 measuring 7.0 cm. We diagnosed the tumor as primary liver cancer and suspected it to be hepatocellular carcinoma(HCC)preoperatively. We performed extended medial segmentectomy and partial hepatectomy of segment 6. The histopathological diagnosis was mixed HCC and primary hepatic neuroendocrine carcinoma(PHNEC). Three months after hepatectomy, the patient died of multiple intrahepatic recurrences. In most of the reported cases of mixed HCC and PHNEC, only the PHNEC component has been detected in the biopsy of the metastatic lesions. This fact might suggest that PHNEC has a higher proliferative activity and malignant potential than HCC. Standard treatment for mixed HCC and PHNEC is unclear; therefore, development of multidisciplinary treatment strategies combining surgical treatment and systemic chemotherapy is required.