The prevalence of cardiovascular diseases has been shown to be on the increase in Africa based on hospital-based information and limited national surveys. A recent report on analysis of data from Health Information Management Systems (HIMS) highlighted an increasing burden of noncommunicable diseases (NCDs) in Eritrea, with the incidence of hypertension doubling in a space of 6 years. HMIS data are only a proxy of national prevalence rates, necessitating the conduct of national surveys. The WHO STEPwise approach to surveillance of NCDs was used for the national NCD risk factor survey in 2004. This report focuses on blood pressure (BP) and obesity (body mass index (BMI) > 30 kg/m2) as NCD risk factors in Eritrea. A total of 2352 people in age groups 15 to 64 years participated in the survey. The prevalence of hypertension defined as BP > 140/90 mmHg was 15.9% in the general population, with 16.4% in urban and 14.5% in rural areas, 17% of whom were males while 15% were females. BMI was positively associated with systolic (SBP), diastolic and mean arterial pressure. Although the prevalence of obesity (3.3%) was higher in females, the effect of BMI on BP was higher in males than in females (regression coefficient 0.64 and 0.38, respectively, P < or = 0.05), especially in those >45 years. BMI did not have a significant effect on BP in lean people (BMI < 19) and in those with high BMI, but was positively correlated to SBP in those with normal BMI (P < or = 0.02). BMI and age appear to play a synergistic role in creating a strong association with BP.