We treated five isoniazid-overdosed patients each with a single dose of pyridoxine hydrochloride equivalent to the gram amount of isoniazid ingested and compared their outcome with that of 41 patients from the literature who received little or no pyridoxine. Recurrent seizures occurred in 60% of patients who had received no pyridoxine vs 0% in our patients. Metabolic acidosis resolved in our cases but was refractory in the literature cases. In our cases, coma lightened more rapidly and was of shorter duration as compared with that in the literature cases (mean, seven hours vs 24 hours). No adverse effects of pyridoxine were seen in our patients.