In ancient Greek mythology, sirens were creatures of stunning beauty whose mystical songs led sailors to sail their boats onto hidden rocks and into total destruction. In this issue, Mason-Osann and colleagues present data in the context of acute myelogenous leukemia to suggest that while synergy may show initial attractions in drug combinations, it may carry with it hazards previously unforeseen. See related article by Mason-Osann et al., p. 95 (1).