Background-—Recent studies have discovered that a-globin is expressed in blood vessel walls where it plays a role in regulating vascular tone. We tested the hypothesis that blood pressure (BP) might differ between normal individuals and those with a+thalassemia, in whom the production of a-globin is reduced. Methods and Results-—The study was conducted in Nairobi, Kenya, among 938 adolescents aged 11 to 17 years. Twenty-fourhour ambulatory BP monitoring and arterial stiffness measurements were performed using an arteriograph device. We genotyped for a+thalassemia by polymerase chain reaction. Complete data for analysis were available for 623 subjects; 223 (36%) were heterozygous (_a/aa) and 47 (8%) were homozygous (_a/_a) for a+thalassemia whereas the remaining 353 (55%) were normal (aa/aa). Mean 24-hour systolic BP _SD was 118_12 mm Hg in aa/aa, 117_11 mm Hg in _a/aa, and 118_11 mm Hg in _a/_a subjects, respectively. Mean 24-hour diastolic BP _SD in these groups was 64_8, 63_7, and 65_8 mm Hg, respectively. Mean pulse wave velocity (PWV)_SD was 7_0.8, 7_0.8, and 7_0.7 ms_1, respectively. No differences were observed in PWV and any of the 24-hour ambulatory BP monitoring-derived measures between those with and without a+thalassemia. Conclusions-—These data suggest that the presence of a+thalassemia does not affect BP and/or arterial stiffness in Kenyan adolescents.