ObjectiveTo assess the public health burden from high blood pressure and the current status of its detection and management in four African-origin populations at emerging or high cardiovascular risk.DesignCross-site comparison using standardized measurement and techniques.SettingRural and urban Cameroon; Jamaica; Manchester, Britain.SubjectsRepresentative population samples in each setting. African-Caribbeans (80% of Jamaican origin) and a local European sample in Manchester.Main outcome measuresCross-site age-adjusted prevalence; population attributable risk.ResultsAmong 1587 men and 2087 women, age-adjusted rates of blood pressure⩾160 or 95 mmHg or its treatment rose from 5% in rural to 17% in urban Cameroon, despite young mean ages, to 21% in Jamaica and 29% in Caribbeans in Britain. Treatment rates reached 34% in urban Cameroon, and 69% in Jamaican- and British- Caribbean-origin women. Sub-optimal blood pressure control (>140 and 90 mmHg) on treatment reached 88% in European women. Population attributable risks (or fractions) indicated that up to 22% of premature all-cause, and 45% of stroke mortality could be reduced by appropriate detection and treatment. Additional benefit on just strokes occurring on treatment could be up to 47% (e.g. in both urban Cameroon men and European women) from tighter blood pressure control on therapy. Cheap, effective therapy is available.ConclusionWith mortality risk now higher from non-communicable than communicable diseases in sub-Saharan Africa and elsewhere, systematic measurement, detection and genuine control of hypertension once treated can go hand-in-hand with other adult health programmes in primary care. Cost implications are not great. The data from this collaborative study suggest that such efforts should be well rewarded.