The progressive lengthening of the average life span and the expanding elderly population high-light the phenomenon of "centenarianism" or extreme longevity in Italy. A large number of Italian Geriatric and Gerontology Centers throughout Italy have joined in the Italian Multicenter Study on Centenarians which evaluates the clinical and biological conditions of centenarians. A census of centenarians in Italy as of December 31, 1993 is presently in course. Preliminary data indicate that about 6000 subjects were alive on that day. Interesting epidemiological and biological information is also being processed. Scores based on the mini mental state, the index of independence in activities of daily living, the instrumental activities of daily living, and the geriatric depression scale, as well as laboratory tests, and case histories have evidenced a number of particular characteristics of centenarians: their longevity is familiar; centenarians live in a familiar and comfortable environment; they have been hard workers, and they have a good degree of mental self-sufficiency; they have never presented the classic risk factors, have always followed a balanced diet based on natural foods; they maintain a well-conserved immune system and especially natural killer activity; they have a normal lipidic balance and no symptomatic hyperglycemia. Mobility and morbidity rates are high. Further studies and interdisciplinary research should enable us to gain better understanding of the aging process and of life "over 100".