Over the past two decades there has been a great deal of interest in the use of anticonvulsants to treat a variety of primary psychiatric disorders. Valproate, one such anticonvulsant, has been found to be effective in the treatment of acute mania, mixed states and rapid cycling disorders. This paper presents the results of an open study with combination therapy of valproate and lithium in a series of nine patients (mean age = 50 years). These patients had previously been treated with various psychotropic agents, including a combination of carbamazepine and lithium. All but one patient showed marked or moderate improvement in their condition. Of particular interest was the observation that in three patients there was evidence of augmentation between valproate and lithium during the depressed phase of their illness. There was significant improvement in their depression within 24 to 48 hours of the addition of lithium to valproate. The combination therapy was very well-tolerated. It is concluded that valproate and lithium combination therapy provides a safe and effective alternative for the treatment of rapid cycling variant of bipolar illness.