Abstract: Life-threatening hepatotoxicity in the setting of acetaminophen overdose is due to depletion of glutathione (GSH), a vital cysteine-containing tripeptide that protects cells and organs against oxidant injury. Rapid administration of N-acetylcysteine (NAC), which provides the cysteine necessary to replenish the depleted GSH, is the standard of care for preventing injury in acetaminophen overdose. Beneficial effects of NAC treatment have also been demonstrated in respiratory, cardiovascular, endocrine and infectious and other diseases. In fact, over fifty randomized placebo-controlled trials conducted in diverse clinical settings document positive responses to NAC treatment.