The authors present the youngest reported case of a single oral overdose of methotrexate in an otherwise well 19-month-old child who was treated with delayed folinic acid rescue. Initial history revealed possible ingestion of up to 10 tablets, each containing 2.5 mg of methotrexate. The peak methotrexate level was 0.67 µmol/l measured 8 h following ingestion. Depending on the protocol, methotrexate levels that remain greater than 0.05-0.1 µmol/l for 24-48 h are associated with risk of toxicity. No adverse sequelae were noted during hospital admission despite delayed folinic acid rescue and there was no evidence of myelosuppression for up to 3 weeks following the overdose.