There is significant public and scientific interest as regards unconventional anticancer agents (complementary and alternative medicine [CAM] agents). This article describes five principles pertaining to the question of which CAM agents should be taken to clinical trial: (1) many CAM agents have been proposed as cancer treatments, far more than could possibly be studied in clinical trials; (2) claims by patients or practitioners are generally unhelpful in choosing which CAM agents to test; (3) laboratory studies can help determine which CAM agents to take to trial and with which cointerventions; (4) preliminary laboratory studies are essential to confirm safety before trials can be considered; and (5) the vast majority of anticancer CAM agents will be ineffective; our aim should be to discard agents from consideration as rapidly as possible.