Centenarians disprove the ageist myth "the older you get, the sicker you get"; they live 90-95% of their very long lives in excellent health, only to experience illnesses in the very last few years of their lives. Thus, it appears that in order to live to 100, one must age relatively slowly and markedly delay and/or escape age-associated diseases. How they achieve such a survival advantage is still a mystery though it is becoming increasingly clear that a substantial genetic advantage plays a role in their ability to live 20-25 years beyond average life expectancy. Current genetic studies of centenarian sibships may yield the identity of some of these genes in the near future. Identifying such genes may yield new information about how people age differently and what modulates differences in susceptibilities to various diseases associated with aging.