The neurological signs, the cerebral CAT scan aspects and the ocular problems seen in five cases of acute methanol poisoning are reported; these were, respectively, coma requiring assisted ventilation, convulsions, hypotonicity, hypodensity of the putamen, and amaurosis and papillary oedema. The simplified acute physiologic score varied from 11 to 26; the value of 26 was observed in the only death of the series. Pathogenesis of the metabolic acidosis, as well as the different parts played by formic acid, lactic acid and ketone bodies are discussed. A normal or lowered serum potassium in a case of unexplained metabolic acidosis associated with an osmotic gap should make one think of the diagnosis. Macrocytosis, an indirect sign of folic acid deficiency, was in favour of a poor prognosis. The treatment included early gastric lavage, alkalinization, blocking of the metabolism of methanol by ethanol and haemodialysis with a bicarbonate dialysate enriched in ethanol; this corrected the acidosis and permitted the elimination of the toxic metabolites (clearance of methanol: 159 ml X min-1; half-life of methanol during purification: 3.46 +/- 1.32 h; quantity extracted: 246 g). The possible advantages of 4-methyl-pyrazol and alkyldiol derivatives need further confirmation.