Objectives: This study aims to investigate the effect of isolated seizures turning into epilepsy on long-term mortality after open heart surgery. Material and Methods: All patients who underwent cardiopulmonary bypass were analyzed retrospectively. Patients with generalized or focal new-onset seizures in postoperative period were eligible for the study. Of them, patients with previous neurological disturbances were kept out of the analysis. Postoperative neurological complications including ischemic or hemorrhagic events were also excluded from the study. Results: Patients with seizure had a substantially higher incidence of operative mortality. Twenty-five epileptic patients (0.88%) were reviewed. Two seizures occurred in 6 patients (24%) in a median of 1 day postoperatively. Three patients (12%) had repeated seizures, 1 (4%) of them had twice. Twenty-four patients (96.0%) were discharged without new-onset neurologic deficit. Conclusions: The emergence and recurrence of a new postoperative seizure in patients may increase the possibility of death in the postoperative hospital and in the long term. Keywords: Open heart surgery, seizures, epilepsy, mortality