This paper analyzes the relationship between age and productivity for Nobel prize winners in science during the period 1901–1992. The relationship found is field dependent as well as dependent upon the definition used to measure the age at which the ward-winning work was done. The results suggest that although it does not require extraordinary youth to do prizewinning work, the odds decrease markedly in mid-life and fall off precipitously after age 50, particularly in chemistry and physics. The discussion underscores the problem of drawing conclusions about the age structure of research by examining medians instead of the entire distribution.