The anticonvulsants, especially carbamazepine and valproate, offer new clinical and theoretical perspectives in the treatment of lithium-refractory bipolar disorders. They appear effective in a group of patients who often respond poorly to lithium, that is, those with rapid cycling illness. Given that these drugs have different profiles of clinical antiepileptic activity and different biochemical mechanisms of action, it is not unexpected that preliminary evidence indicates that some affectively ill patients may selectively respond to one, but not the other, agent. It remains to be determined whether common mechanisms underlie the anticonvulsant and psychotropic effects and whether "limbic" actions are important to their properties in affective illness. The potential role of valproate in acute and long-term treatment of bipolar illness deserves further controlled evaluation given the preliminary data summarized in the series of papers in this volume.