Tetrahydroisoquinoline derivatives were synthesized and their multidrug resistance reversal activities were evaluated in vitro. The results showed that some of the synthetic compounds had higher multidrug resistance (MDR) reversal activities than verapamil. Tetrahydroisoquinoline derivatives were synthesized and their multidrug resistance reversal activities were evaluated in vitro. The results showed that some of the synthetic compounds had higher multidrug resistance (MDR) reversal activities than verapamil.