OBJECTIVE: To report oxaprozin-induced fulminant hepatic failure. CASE SUMMARY: A 56-year-old woman was admitted with fulminant hepatic failure. Work-up for potential etiologies was negative except for the use of oxaprozin for the preceding two months. Results of premortem liver biopsy were consistent with drug-induced hepatic injury similar to that previously reported with diclofenac. DISCUSSION: Although the literature describes elevation in hepatic transaminase concentrations associated with oxaprozin, fulminant hepatic failure has not been described previously. CONCLUSIONS: Elevations in hepatic transaminase concentrations and now fulminant hepatic failure have been shown to occur with oxaprozin, as previously seen with other nonsteroidal antiinflammatory drugs (NSAIDs). Transaminitis is a known adverse effect of NSAID use, but is usually mild and reversible with discontinuation of drug. Transaminitis may be more likely to occur in the elderly, in patients receiving concurrent potentially hepatotoxic medications, and possibly with the newer long-acting NSAIDs. The existence of fulminant hepatitis, although rare, supports the need for monitoring liver function enzymes during NSAID therapy.