The pyogenic liver abscess is an uncommon but potentially lethal complication of colo-anal surgery. The authors report a case due to Streptococcus intermedius, a pathogen with a known ability to produce visceral abscesses, after haemorrhoidectomy. According to the French consensus conference, the patient had received a prophylactic preoperative antibiotic regimen consisting of metronidazole, active against S intermedius. Despite surgical therapy and adequate antibiotics, the patient died of hepatic failure.