Spontaneous bacterial peritonitis is a well-known entity, with a reported incidence of 15-20% in advanced cirrhotic patients. Escherichia coli and Klebsiella pneumoniae are the most common causes of spontaneous bacterial peritonitis; Brucella is extremely rare. We aimed to present one case of such a rare condition in a cirrhotic patient who also had hepatocellular carcinoma. Routine laboratory tests, abdominal ultrasonography and peritoneal fluid examinations were studied in a cirrhotic patient with ascites. Peritoneal fluid white blood cell count was 1300/mm3, with lymphocyte predominance (80%). Peritoneal fluid and blood culture both yielded Brucella melitensis. The patient also had a mass in the right lobe of the liver confirmed as hepatocellular carcinoma by biopsy. Brucella should be suspected as a cause of spontaneous bacterial peritonitis in cirrhotic patients with no response to standard spontaneous bacterial peritonitis treatments and with immunodeficiency such as hepatocellular carcinoma.