OBJECTIVE: The purpose of the present study was to identify sources of variability for systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) in a sample of adult African-American twins. DESIGN: The classic twin design was employed to examine genetic and environmental sources of variance in the outcome measures of interest. PARTICIPANTS: Participants were 143 (71 MZ and 72 DZ) same-sex, intact twin pairs (mean age = 49.87 years; SD 13.62), who took part in the Carolina African-American Twin Study of Aging (CAATSA). MAIN OUTCOME MEASURES: Outcome measures of interest included SBP and DBP, and PP. RESULTS: For older twins, heritabilities were .52 for SBP, .36 for DBP, and .14 for PP. However, for younger twins, heritabilities were .44 for SBP, .27 for DBP, but no genetic influence on PP was observed. CONCLUSION: The results indicate that genetic factors are a significant source of variance in hemodynamic indices, and also suggest that, with advancing age, genetic factors play an increasing role in determining blood pressure and PP in this population.