We report on a case of spontaneous bacterial peritonitis (SBP) due to Haemophilus influenzae (H. influenzae) in an elderly patient with alcoholic cirrhosis. The patient presented with a 5 day history of fever, cough, and fatigue. Abdominal paracentesis revealed a very high neutrophil count (134,800 cells/μL). Secondary peritonitis and abdominal abscess were ruled out. Peritoneal fluid culture displayed the growth of H. influenzae. The patient was treated with ceftriaxone and showed signs of improvement. Eventually, the patient died due to septic shock caused by other organisms. H. influenzae is a very rare cause of SBP. This case report demonstrates that (1) H. influenzae should be considered a potential cause of SBP, and (2) a very high leukocyte count in ascitic fluid can be found in patients with SBP.