We determined underlying cause-specific mortality for incident unprovoked seizures from Northern Manhattan, New York City. We calculated the case fatality, proportionate mortality, and the underlying cause-specific standardized mortality ratios (SMRs), with U.S. death rates as the standard. Thirty-two deaths were observed between 2003 and 2007 among 209 participants. Case fatality was significantly lower for idiopathic/cryptogenic seizures versus symptomatic seizures. About 31.3% of the deaths were attributed to malignant neoplasms, 25.0% to diseases of the heart, 15.6% to influenza and pneumonia, 3.1% to cerebrovascular diseases, and 25.0% to other causes. Significant SMRs were observed for all causes (SMR = 1.6), influenza and pneumonia (SMR = 7.1), and malignant neoplasms (SMR = 2.9). Younger cases (<65 years) had increased SMRs for all causes, malignant neoplasms, and other causes. Older cases (> or =65 years) had increased SMRs for influenza and pneumonia. Underlying cause of death paralleled the underlying cause of seizure in patients with symptomatic etiologies.