4-Cyanopyridine is used as an intermediate in organic synthesis and pharmaceutical substances like isonicotinylhydrazide, which is used in the treatment of tuberculosis. It is used as a precursor for the preparation of isonicotinic acid and 4-diemthylaminopyridine (DMAP). It is involved in the synthesis of 6-methyl-2-pyridin-4-yl-pyrimidin-4-ylamine by reacting with acetonitrile.