Background: The incidence of reported acute renal failure (ARF) due to methotrexate is about 1.8%. Although standard of care of this condition includes hyperhidration and leucovorin rescue, hemodialysis may be considered in some cases.
Case Report: We present the case of a 13-year-old girl with a relapsed osteosarcoma three months after the end of first treatment. Three pulmonary nodes were removed and after she received intravenous methotrexate (12 g/m²) she developed a severe ARF, seizures and pancytopenia. The patient underwent to hemodialysis and folinic acid rescue. She recovered and is in complete remission with normal renal function 60 months after the end of the treatment.
Conclusions: Although the indication of hemodialysis is not a consensus, we suggest this procedure should be indicated to treat severe ARF due to methotrexate when Carboxypeptidase G2 is not readily available.

Keywords: Acute renal failure (ARF), adverse effects, Methotrexate, hemodialysis