Blood pressure and anthropometric measurements were obtained according to a standardized protocol in two biracial, rural, southern communities. Essentially, the same examination team and protocol were used in Franklinton and Bogalusa. No differences between the communities in mean height or weight (except for white boys) were observed. Blood pressure levels were 2-5 mm Hg higher in Franklinton, particularly in blacks ages 8-13 years. These differences could not be explained by differences in anthropometric measurements or observers. The difference may be due partly to the fact that larger numbers of students each morning were examined in Franklinton than Bogalusa in perhaps a more hurried environment. Most of the staff members, being from Bogalusa, were not familiar to the children in Franklinton (as they are in Bogalusa), and this may have created anxiety. The differences were small, however, when compared with differences observed among several populations using varying methods. Confirmation is given to the finding that height and weight, not age, are the strongest determinants of blood pressure level in growing children, giving a further clue toward development of an appropriate definition of hypertension in children.