Obesity is an important risk factor for hypertension, but epidemiologic studies provide evidence for the development of hypertension independent of obesity. In addition, the search for hypertension susceptibility genes should prove more informative when applied to a homogeneous subset of patients, such as those that are not obese. For this reason, we sought to identify genomic regions influencing susceptibility to hypertension in a nonobese sample of hypertensive African American families.A genome-wide linkage scan was performed in a sample of 275 African American hypertensive families containing two or more nonobese (body mass index, < or = 30 kg/m2) individuals recruited by Networks of the Family Blood Pressure Program (FBPP).The best evidence for linkage of hypertension among the FBPP African American families was found on chromosome 2 (log of the odds [LOD]= 3.59 at 230 cM). All other chromosomes contained LOD scores less than 2. The African American sibships from the GENOA Network appear to largely contribute to the evidence for linkage on chromosome 2 (LOD = 4.07 at 233 cM).Significant evidence for linkage to hypertension in nonobese African American families was identified on chromosome 2q. These results suggest the presence of genes influencing susceptibility to adiposity-independent hypertension.