The association between intrauterine growth retardation and blood pressure in middle childhood and early adulthood was examined. At age 7, after adjusting for sex and weight, the differences between normal children and those who had experienced intrauterine growth delay were 0.9 mmHg (95% CI -0.1 to 2.2) for systolic and 0 mmHg (-1.7 to 2.0) for diastolic blood pressure respectively. The differences between the blood pressures of intrauterine growth retarded infants with an appropriate ponderal index and those with a low ponderal index were 4.4 mmHg (-0.9 to 7.9) for systolic, and 3.8 mmHg (0.2 to 7.3) for diastolic blood pressure respectively. At age 18 the differences were much less pronounced. The association between blood pressure and the placental weight was also examined. The evidence from this sample lends weak support to the findings of other studies which suggest that there is an association between factors occurring before or around the time of birth and blood pressure in later life.