OBJECTIVE: To assess the link between maternal diet during pregnancy and blood pressure of the offspring. DESIGN: Follow-up study. SETTING: A university hospital in Amsterdam, The Netherlands. PARTICIPANTS: People born at term as singletons between November 1943 and February 1947. MAIN OUTCOME MEASURE: Blood pressure at adult age. RESULTS: Adult blood pressure was not associated with protein, carbohydrate or fat intake during any period of gestation. We found, however, after adjustment for sex that the systolic blood pressure decreased by 0.6 mmHg (0.1-1.1) for every 1% increase in protein/carbohydrate ratio in the third trimester. This association was present both in people who had been exposed to the famine during gestation as well as in those who had not been exposed. The association between protein/carbohydrate ratio in the third trimester and adult blood pressure was furthermore independent of maternal weight gain and final weight, and birth weight [increase for every 1% increase in protein/carbohydrate ratio 0.6 mmHg (0.0-1.2)]. Adjustment for adult characteristics such as body mass index, smoking and socio-economic status did not affect the observed association appreciably [adjusted increase 0.5 mmHg (0.0-1.0)]. CONCLUSION: Adult blood pressure seems to be affected by small variations in the balance of macro-nutrients in the maternal diet during gestation rather than by relatively large variations in the absolute amounts.