The 1,4-dihydropyridine (1,4-DHP) and 1,4-dihydroindeno[1,2-b]pyridine (1,4-DHIP) derivatives were investigated as glutathione S-transferase (GT) inhibitors. The obtained results indicate that some of the 1,4-DHP's containing lipophylic and bulky substituents have inhibitory effects on GT in vitro. The derivatives of 1,4-DHIP are more pronounced inhibitors.