BACKGROUND: Synchronous occurrence of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC) is extremely rare. CASE: A 67-year-old male was admitted to the hospital with hemoperitoneum caused by a liver mass rupture and elevated serum liver enzymes. Abdominal magnetic resonance imaging revealed a solid mass, with 38 mm in maximum diameter, located in the fifth/sixth segments of the liver, suggesting an HCC. Emergency surgery was performed and a second liver mass in the fourth segment was identified intraoperatively, with 20 mm in maximum diameter. Hepatic resection of the affected segments was performed with free resection margins. Histopathological examination revealed the synchronous occurrence of HCC and ICC with a predominant ductal plate malformation pattern. The patient is still alive at 41 months after its first surgery. CONCLUSIONS: In patients with HCC, a proper intraoperative assessment is indicated, in addition to imaging investigations, to detect synchronous lesions that can change the therapeutic approach. This is the first case ever reported in the literature in which synchronous HCC and ICC with a predominant ductal plate malformation pattern were incidentally diagnosed in a patient with hemoperitoneum.