A review.Phytohemagglutinin (PHA), Con A (Con A), and pokeweed mitogen (PWM) have been key laboratory mitogens for many years during which their clin. applications have failed to evolve at an acceptable rate.PHA, the first mitogen identified, has been the one whose therapeutic potential has been most widely studied and ultimately the only one applied in humans.Con A intensely investigated by Morris showed clin. promise until unique lethal reactions in dogs have restricted its use to the laboratoryPWM has captured the limelight because of its high potency and its successful albeit inadequately exploited applications for malignancies in dogs and cats.PHA-fraction IV developed by Goldberg's group shows promise as a nonagglutinating alternative to PHA.The salient features of these four compounds are reviewed here emphasizing their generally unrecognized curative potential when given either alone or in conjunction with other therapeutic agents.Highly sophisticated products now advanced to market commonly exhibit limitations of various types that might be overcome by the enhancing effects of mitogens.