Hypertension is a major and fast-growing public health problem in Africa. We determined the prevalence of hypertension and assessed the levels of awareness, treatment and control in Guinea. A cross-sectional study based on a stratified cluster random sampling was conducted. In all, 2491 adults (1351 women) aged 15-64 years were selected and screened during September-December 2009. Hypertension (systolic (and/or diastolic) blood pressure ⩾140 (90) mm Hg or use of antihypertensive medications) and diabetes mellitus (fasting capillary glucose ⩾110 mg dl(-1) or use of antidiabetic medications) were determined. Logistic regressions were used to investigate the determinants of hypertension. The mean body mass index was 22.4 kg m(-2) (s.d.=4.5). The prevalence of hypertension and diabetes was, respectively, 29.9% (95% confidence interval (CI) 29.8-30.0) and 3.5% (95%CI 3.4-3.5). The prevalence of hypertension was 29.4% (29.3-29.5) in men and 30.4% (30.4-30.6) in women. The prevalence was 62.5% in the 44-64 years age group. Overall, 75.8% of hypertensive participants were undetected before the survey and 34.9% of those aware of their hypertensive status were receiving treatment, of whom 16.3% were at target control levels. Age, education, diabetes and obesity were the main factors associated with hypertension. There was a high prevalence of hypertension among the adults in Guinea, but with low awareness, treatment and control rates. Urgent response is needed in the form of integrated and comprehensive action targeting major non-communicable diseases in the country.