METHODS A 41-year -old man was admitted for resection of several liver segments, because a malignant tumor was suspected. He had two years previously sustained blunt trauma to the abdomen and chest. At that time a hematoma of the liver had been diagnosed by ultrasound and computed tomography. Follow-up imagings showed an increase in its size. On admission the patient had only slight right upper abdominal pain; laboratory tests were unremarkable. METHODS Computed tomography confirmed the suspected diagnosis of a cholangiocellular carcinoma with possible abdominal wall infiltration. Tumor markers were negative. METHODS An extensive partial liver resection was performed. Histological examination of the resected specimen revealed solid actinomycosis of the liver. After prolonged high dosage penicillin treatment all signs and symptoms resolved without further problems. Postoperative serology provided no evidence of active systemic actinomycosis. CONCLUSIONS This case demonstrates the difficulty of diagnosing and treating solid actinomycosis.