The invention relates to a method for the prevention and/or treatment of renal toxicity, nephrosis or nephritis, which comprises administering a pyrazolopyridine compound of the formula: ##STR1## wherein R.sup.1 is aryl, andR.sup.2 is unsaturated heterocyclic group which contains at least one heteroatom selected from the group consisting of N, O and S, which may have one or more suitable substituent(s), or a pharmaceutically acceptable salt thereof to a human being or an animal.