The effects of dietary gamma-linolenic acid supplementation in the form of evening primrose oil were examined in pregnant zinc-deficient rats and subsequently in their newborn pups. This supplementation was beneficial, since it reduced pup mortality, increased mean litter size and maintained appetite throughout two thirds of the gestation period. Consequently, gamma-linolenic acid seems to correct some of the biological effects of zinc deficiency. It is suggested that evening primrose oil could be used in cases of zinc deficiency caused by metabolic disturbances.