Primary or secondary IGF1 deficiency has been implicated in shortening of lifespan. This paper reviews available data on the influence of IGF1 deficiency on lifespan and longevity in animals and man. It has been shown that inactivation of the IGF1 gene or of the GH receptor in both invertebrates (C-elegans, flies-Drosphila) and rodents (mice and rats), leading to IGF1 deficiency, prolong life, particularly in females. In man, evaluation of the 2 largest cohorts of patients with Laron syndrome (inactive GH receptor resulting in IGF1 deficiency) in Israel and Ecuador revealed that despite their dwarfism and marked obesity, patients are alive at the ages of 75-78 years, with some having reached even more advanced ages. It is assumed that a major contributing factor is their protection from cancer, a major cause of death in the general population.