Cross-sectional univariate and multivariate analyses estimated differences between the blood pressure of adult Tokelauan migrants to New Zealand and non-migrants still living on three Polynesian atolls. Response rates were 97 and 99% in the two locations. Among males, the difference between migrants and non-migrants after adjustment for significant covariates was 7.2 mmHg systolic pressure (p less than 0.001) and 8.1 mmHg diastolic pressure (p less than 0.001). Among females, adjusted systolic pressure was not significantly higher in migrants compared to non-migrants (1.8 mmHg, p = 0.065) and diastolic pressure was only 3.0 mmHg higher (p less than 0.001). Body mass is significantly correlated with blood pressure in this study group; nonetheless, differences in body mass explain only a small proportion of the observed migrant/non-migrant differential in blood pressure. Estimates of blood pressure differences preceding migration are also reported. These indicate that blood pressure was neither consistently nor significantly higher among those who subsequently migrated. This report provides compelling evidence linking Westernization and the development of chronic disease.