The relationship between social network and blood pressure was assessed in a cross-sectional, random sample of 1409 white adults aged 20 to 70 years studied in Buffalo in 1961. Higher total social network scores were associated with lower systolic and diastolic blood pressure in both males and females. Considering the components of social network separately, increased size of household and greater participation in clubs were associated with lower systolic blood pressure for males, with the trend in the same direction for women, though not reaching statistical significance. Among females, the only social network component showing significant linear trend was the number of siblings, with increased number of siblings being associated with lower systolic and diastolic blood pressure. Religious service attendance and marital status were not associated with blood pressure in this population.