BACKGROUND Combined hepatocellular carcinoma and cholangiocarcinoma (cHCC-CC) is an uncommon subtype of primary liver cancer that has rarely been reported in large-scale clinical studies. The aim of this study was to clarify the clinical features, treatment modalities, and prognosis of cHCC-CC. METHODS Included in this study were 113 patients who were histologically diagnosed as having Allen type C cHCC-CC, 103 of whom received liver resection, 6 transarterial chemoembolization treatment, 3 radiofrequency ablation, and 1 palliative supportive treatment. Clinicopathologic features and prognosis of 103 cHCC-CC patients after liver resection were compared with those of 6,679 patients with hepatocellular carcinoma (HCC) and 386 patients with intrahepatic cholangiocarcinoma (ICC) who underwent liver resection during the same period. RESULTS The proportion of cHCC-CC in primary liver cancers was 1.5 %. The 103 cases of cHCC-CC were characterized by male predominance, infection with hepatitis virus or presence of liver cirrhosis, and elevated alfa-fetoprotein-findings similar to HCC. However, serum CA19-9 elevation, incomplete capsules, and lymph node involvement were similar to ICC. The 1-, 3-, and 5-year overall survival rates after liver resection were 73.9, 41.4, and 36.4 %, respectively, for patients with cHCC-CC versus 77.5, 53.3, and 41.4 % for HCC patients, and 58.0, 29.1, and 22.3 % for ICC patients (χ(2) = 137.5, P < 0.001). Tumor, node, metastasis system stage (hazard ratio 1.27, 95 % confidence interval 1.08-1.49, P = 0.003) and radical liver resection (hazard ratio 0.31, 95 % confidence interval 0.14-0.68, P = 0.004) were independent prognostic factors for overall survival. CONCLUSIONS cHCC-CC has biological behavior and prognosis that are intermediate between HCC and ICC. Radical liver resection can provide a better outcome for this uncommon malignancy.