Myoclonus is a movement disorder of various etiologies. An alteration in CNS serotonin activity is hypothesized to be the underlying mechanism for several myoclonic syndromes. Myoclonus has been reported as a side effect of antidepressants, and the serotonin hypothesis has been advanced to include this syndrome. A case is reported of myoclonus induced by an antidepressant purported to have no effect on serotonin activity.