To compare the risk of mortality of nonagenarian siblings with that of sporadic nonagenarians (not selected on having a nonagenarian sibling) and to compare the prevalence of morbidity in their offspring with that of the offsprings' partners. Longitudinal (mortality risk) and cross-sectional (disease prevalence). Nationwide sample. The Leiden Longevity Study consists of 991 nonagenarian siblings derived from 420 Caucasian families, 1,365 of their offspring, and 621 of the offsprings' partners. In the Leiden 85-plus Study, 599 subjects aged 85 were included, of whom 275 attained the age of 90 (sporadic nonagenarians). All nonagenarian siblings and sporadic nonagenarians were followed for mortality (with a mean+/-standard deviation follow-up time of 2.7+/-1.4 years and 3.0+/-1.5 years, respectively). Information on medical history and medication use was collected for offspring and their partners. Nonagenarian siblings had a 41% lower risk of mortality (P<.001) than sporadic nonagenarians. The offspring of nonagenarian siblings had a lower prevalence of myocardial infarction (2.4% vs 4.1%, P=.03), hypertension (23.0% vs 27.5%, P=.01), diabetes mellitus (4.4% vs 7.6%, P=.004), and use of cardiovascular medication (23.0% vs 28.9%, P=.003) than their partners. The lower mortality rate of nonagenarian siblings and lower prevalence of morbidity in their middle-aged offspring reinforce the notion that resilience against disease and death have similar underlying biology that is determined by genetic or familial factors.