Abstract: The present invention comprises methods and compositions for reducing or eliminating multidrug resistance in cancers or certain infections by drug resistant microorganisms in patients. According to the method and composition of the present invention, a non-ionic amphipathic diester of fatty acids or a reverse poloxmer is administered to a patient in which a cancer or microorganism exhibits multidrug resistance to the chemotherapeutic agent. The method and composition of the present invention may be employed with particular efficacy where multidrug resistance to any chemotherapeutic agent has been conferred upon a cancer.