ObjectiveTo describe the prevalence, detection, treatment and control of hypertension in an urban and rural area of Tanzania.DesignTwo linked cross-sectional population-based surveysSettingA middle-income urban district of Dar es Salaam (Ilala) and a village in the relatively prosperous rural area of Kilimanjaro (Shari)ParticipantsSeven hundred and seventy adults (> 15 years) in Ilala and 928 adults in Shari were studiedResultsHypertension prevalence (blood pressure >140 and/or 90 mmHg, or known hypertensives receiving antihypertensive treatment) was 30% (95% confidence interval, 25.1–34.9%) in men and 28.6% (24.3–32.9%) in women in Ilala, and 32.2% (27.7–6.7%) in men and 31.5% (27.8–35.2%) in women in Shari. Age-standardized hypertension (to the New World Population) prevalence was 37.3% (32.2–42.5%) among men and 39.1% (34.2–44.0%) in women in Illala, and 26.3% (22.4–30.4%) in men and 27.4% (24.4–30.4%) in women in Shari. In both areas, just under 20% of hypertensive subjects were aware of their diagnosis, approximately 10% reported receiving treatment and less than 1% were controlled (blood pressure < 140/90 mmHg). Hypertensive subjects were older, had greater body mass indices and waist: hip ratios, and had more risk factors for hypertension and its complications (smoking, heavy alcohol consumption, physical inactivity, obesity and diabetes) than nonhypertensives.ConclusionsThere is a high prevalence of hypertension in rural and urban areas of Tanzania, with low levels of detection, treatment and control. This demonstrates the need for cost-effective strategies for primary prevention, detection and treatment of hypertension and the growing public health challenge of non-communicable diseases in Sub-Saharan Africa.