The diet of the wild boar Sus scrofa Linnaeus, 1758 in a Mediterranean area, where agricultural crops were not available and supplementary food was not provided, is described. Diet was compared to the availability of the main food resources and their influence on body weight and reproduction was investigated from 1991 to 1994. Diet varied according to the availability of energy-rich foods such as acorns and olives; pine-seeds were actively consumed, even when their availability was low. When abundant, acorns and olives accounted for most of the diet, and when scarce were replaced by graminoids and juniper berries. In summer, graminoids and pine-seeds accounted for most of the diet. Acorn and olive production was likely to influence both body weight and reproduction. Following a high production of acorns and olives, wild boar exhibited higher body weight, more breeding females and a larger litter size than in years of poor production of these foods.