We describe four patients who developed an encephalopathic syndrome ch
aracterized by obtundation or stupor, myoclonic jerks, and asterixis i
n association with cefuroxime therapy. Three patients had renal failur
e. These cases suggest that cefuroxime in overdose or in conventional
doses in patients with renal failure can cause a reversible encephalop
athy. This syndrome may have been unrecognized because it usually occu
rs in severely ill patients with additional causes for encephalopathy.