We investigated the influence of dietary polyunsaturated fatty acids (PUFA) on the blood pressure of spontaneously hypertensive rats (SHR). Feeding male adult SHR a linoleic acid (LA) rich or a PUFA poor diet did not alter the systolic blood pressure during a two months regimen. Feeding young male SHR an LA rich or a PUFA deficient diet beginning in the prehypertensive phase did not influence the development of hypertension. But when the regimen was begun in the pregnant mothers during the last week of pregnancy and continued in the offspring, the male offspring showed a significantly reduced increase in blood pressure when fed with an LA rich or a linolenic acid rich diet compared with PUFA deficient fed rats. This effect was not so markedly expressed in the female offspring.