To identify the prevalence of hypertension among adults in Bo, Sierra Leone.Hypertension data were extracted from outpatient clinic records.Mercy Hospital in urban Bo, Sierra Leone.All nonpregnant outpatients aged -15 years seen at the outpatient clinic in 2009.Prevalence of hypertension, defined as a systolic blood pressure > or = 140 mm Hg and/or a diastolic blood pressure > or = 90 mm Hg.Data from 3944 individuals were analyzed (mean age 38.7 years). The overall prevalence of hypertension among those aged > or = 15 years was 25.2%, with an age-adjusted prevalence of 19.6%. The prevalence of hypertension for participants aged > or = 20 years was 27.1%, with an age-adjusted prevalence of 23.6%. There were no significant differences in blood pressure by sex. The prevalence of hypertension increased significantly with age for both males and females (P < .001).The prevalence of hypertension in Sierra Leone is consistent with the rates of hypertension observed in other parts of West Africa.