This report examines mortality rates for twins with recorded diagnoses of schizophrenia or neurosis. Mortality patterns in monozygotic & dizygotic pairs discordant for schizophrenia & neurosis showed that mortality cannot be due to the disease state per se; disease-related mortality in schizophrenia results largely from environmental factors shared by twins; mortality from trauma in schizophrenia & from diseases in neurosis results largely from genetic factors. Study limitations are elaborated.