Novel 2-chloro-1,4-dihydropyridine derivatives were synthesized by chlorination of 2-hydroxy-1,4-dihydropyridines with POCl3. The dihydropyridines chlorinated at position 2 exhibited more potent vasodilative and hypotensive activities than the dihydropyridines (nicardipine and nitrendipine) with a methyl group at position 2.