There is now convincing evidence that Streptococcus milleri is an important cause of pyogenic liver abscesses. The clinical course is no different from that of pyogenic infections of the liver arising from other causes. A positive blood culture should alert the clinician to the possibility of hepatic suppuration. Treatment consists of drainage by laparotomy or percutaneous aspiration combined with approximately 6 weeks of penicillin administration. Patients with liver abscesses who receive metronidazole may not respond if S. milleri is the infecting organism.