synthesized and evaluated as multidrugresistance (MDR) reversalagents. The compounds were tested on S1-B1-20 human colon carcinoma cells selected for resistance to bisantrene. Both the cytotoxicity of the reversalagents and their ability to resensitize the cells to bisantrene were determined. All but two of these compounds (15q, 40) were more effective MDR reversalagents in vitro than verapamil (VRP)