A case is presented of the occurrence of an episode of mania apparently induced by desvenlafaxine, in a patient with a history of major depressive disorder and no apparent history of previous mania or hypo-mania. To our knowledge, this is the first such documented case with this new antidepressant. The discussion focuses on the concept of the bipolar spectrum, and how to view patients who have only become manic while taking antidepressants.