OBJECTIVES: To analyse trends during 1980-2011 in hypertension prevalence and SBP/DBP by sex in Fiji Melanesian (i-Taukei) and Indian adults aged 25-64 years; and to assess effects of BMI. METHODS: Unit record data from five population-based surveys were included (n = 14, 191). Surveys were adjusted to the nearest previous census to improve national representativeness. Hypertension was defined as SBP at least 140  mmHg and/or DBP at least 90  mmHg and/or on medication for hypertension. Regression (Poisson and linear) was used to assess period trends. RESULTS: Over 1980-2011 hypertension prevalence (%) and mean blood pressure (BP) (SBP/DBP mmHg) increased significantly (P < 0.001) in both sexes and ethnicities. Increases in hypertension were: from 16.2 to 41.3% in i-Taukei men (mean BP from 122/73 to 135/81); from 20.5 to 37.8% in Indian men (mean BP from 122/74 to 133/81); from 25.9 to 36.9% in i-Taukei women (mean BP from 126/76 to 132/81); and from 17.6 to 33.1% in Indian women (mean BP 117/71 to 130/81). The age-adjusted trend in hypertension and mean BP (over 32 years) declined after adjusting for BMI, with effects of obesity greater in women than men, and in Indians than i-Taukei. BMI explained 45% of the age-adjusted increase in DBP over the period in Indians (both sexes), and 16% (men) and 38% (women) in i-Taukei. CONCLUSION: Significant increases have occurred in hypertension prevalence and SBP/DBP in both sexes and ethnicities of Fiji during 1980-2011 with no indication of decline, contributing to significant premature mortality from cardiovascular disease.