Three dialysis patients with extrapulmonary tuberculosis developed confusion 4-14 days after commencement of treatment with anti-tuberculosis drugs, despite the use of prophylactic pyridoxine. Full recovery of conscious state resulted within 1 week in all patients after stopping isoniazid. In 2 patients confusion recurred on rechallenge of the drug. The risk factors of isoniazid induced encephalopathy and the dosage of isoniazid in uraemic patients were discussed.