During the last decade the psychiatric aspects of liver transplantation have been widely described. Although affective complications are some of the most prevalent, a complete and persistent bipolar II syndrome following transplantation has never been reported before. In this paper we describe a patient who developed a rapidly cycling bipolar II disorder after liver transplantation. He presented a major depressive episode within the first 48 hours following transplantation, and subsequently started cycling from depression to hypomania with only brief periods of euthymia. One year after transplantation, only lithium carbonate has proved to be useful to ameliorate his persistent disorder. There was no premorbid or family history of affective illness. Although the course of the disorder seemed to be independent from any pharmacologic or psychosocial factor, it is suggested that transplantation, corticosteroids, and cyclosporine may have played some role in the pathogenesis of the syndrome.