Toxicity of meta or 3-hydroxyacetanilide was evaluated in mice. The LD50 was 1025 mg/kg when given intraperitoneally (i.p.). The drug in doses greater than 400 mg/kg i.p. caused significant sedation. 3-Hydroxyacetanilide, 900 mg/kg i.p., did not cause hepatic necrosis evaluated by either histology or changes in plasma glutamate pyruvate transaminase activity. Acetaminophen (4-hydroxyacetanilide, paracetamol) caused significant liver glutathione depletion two hours after dosing. In contrast, liver glutathione was only slightly decreased by 600 mg/kg i.p. of 3-hydroxyacetanilide at 2 or 4 hours after the dose. It is suggested that the meta-substituted acetanilide derivatives might be safer analgesics and antipyretics than acetaminophen.