The metabolic effects of intravenous administration of 200 mg/kg imidazole-4-acetic acid (IMA) on normoxic, hypoxemic and hypoxemic-oligemic rat brain were assessed by measurement of the cerebral contents of energy phosphates and selected glycolytic-citric acid cycle intermediates. In normoxic brain IMA was associated with unaltered adenylates, increased glucose and aspartate, and decreased pyruvate, lactate, citrate, alpha-ketoglutarate and malate; a pattern which is compatible with cerebral metabolic depression. In hypoxemic brain IMA was associated with a lower accumulation of lactate and a higher level of tissue glucose; again conforming to patterns documented for classical cerebral depressants. In hypoxemic-oligemic brain IMA was associated with a gross deterioration of the tissue ATP content and with a massive lactacidosis which indicated a detrimental action in this hypoxic state.