The majority of patients with bipolar affective disorder will continue to have some recurrences of acute illness despite lithium maintenance. In a significant proportion, the frequency and severity of acute episodes necessitate the administration of adjunctive maintenance medications. Neuroleptic drugs are often used for this purpose, but anticonvulsant drugs (carbamazepine, valproate, clonazepam) are reported to have acute antimanic efficacy and may offer an alternative for some bipolar patients. We report preliminary results of an open, prospective study in which bipolar patients maintained on lithium and a neuroleptic switch to lithium and clonazepam or continue their prior treatment with lithium and neuroleptic.