The present invention relates to the use of PDGF receptor tyrosine kinase inhibitors, especially of N-phenyl-2-pyrim-idine-amine derivatives of formula (I), in which the symbols and substituents have the meaning as defined herein in free form or in pharmaceutically acceptable salt form, in the manufacture of a pharmaceutical composition for the treatment of diabetic nephropathy; to a method of treatment of warm-blooded animals, including humans, suffering from diabetic nephropathy; and to the use of a PDGF receptor tyrosine kinase inhibitor of the formula (I), wherein R.sub.1 is pyridyl bonded at a carbon atom, R.sub.2, R.sub.3, R.sub.5, R.sub.6 and R.sub.8 are each hydrogen, R.sub.4 is lower alkyl, R.sub.7 a radical of formula (II): --N(R.sub.9)--C(.dbd.X)--(Y).sub.n--R.sub.10, wherein R.sub.9 hydrogen, X is oxo, n is 0 and R.sub.10 is 4-methyl-piperazinyl-methyl, or a pharmaceutically acceptable salt thereof for the manufacture of a medicament for treating glomerulonephritis, chronic pyelonephritis or IgA nephropathy.