6 p. 100 of a population of 129 heart transplant recipients presented isolated convulsions under cyclosporin (Ci) immunosuppressive treatment. These seizures were unexplained by acute causes, infectious or cerebro-vascular. Seizures started generally a few days after Ci therapy onset, and led often to severe convulsive states, with sometimes a status epilepticus. For most of them, Ci serum levels were within, or just above, the recommended therapeutic range. Ischemic brain damage that occurred prior to surgery and Ci therapy, could be a contributing factor to Ci-induced seizures in this population of heart transplant recipients.