The dynamics of the giraffe population of the Serengeti were quantified to ascertain the response of the population to the increasing biomass of the available browse resource. Aerial counts conducted in 1971 and 1976 together with analyses of fecundity and mortality data suggest a rate of population increase of some 5-6% per annum. Compared with the dynamics of a stable giraffe population in Nairobi National Park, the sub-adult components of the Serengeti regional populations are larger and juvenile growth rates