BACKGROUND: Telithromycin is a ketolide antibiotic approved by the U.S. Food and Drug Administration for acute bacterial infections causing sinusitis, bronchitis, and community-acquired pneumonia. OBJECTIVE: To describe 3 cases of severe hepatotoxicity in patients receiving telithromycin. DESIGN: Case reports. SETTING: A tertiary care medical center. PATIENTS: 3 previously healthy patients who had recently taken telithromycin and took no other prescription medications. MEASUREMENTS: Serologic, histologic, and liver function tests. RESULTS: Within a few days of receiving telithromycin, the patients presented with acute hepatitis. All had jaundice and markedly abnormal results on liver function tests. Results of viral serologic tests were negative. One patient spontaneously recovered, 1 required orthotopic liver transplantation, and 1 died. Histologic examination in the latter 2 patients showed massive hepatic necrosis. LIMITATIONS: Two patients had some history of alcohol use. The frequency of severe telithromycin-related hepatotoxicity cannot be established with case reports. CONCLUSIONS: Telithromycin can cause severe hepatotoxicity. Caution is advised in prescribing this drug pending additional postmarketing surveillance data.