Many Korean American persons have hypertension, but competing life priorities often prevent them from attending health-promotion educational activities. Using principles of community-based participatory research, the authors conducted a prospective clinical trial to determine the effectiveness of a mailed vs an in-class culturally tailored education intervention. A total of 380 hypertensive Korean American persons from the Baltimore/Washington area were assigned to a more intense in-class education group or a less intensive mail education group. Evaluation of postintervention blood pressure (BP) outcomes revealed that significant reductions in systolic BP (13.3 mm Hg and 16.1 mm Hg, respectively) and diastolic BP (9.5 mm Hg and 10.9 mm Hg) and increases in BP control rates (42.3% and 54.3%) were achieved in both groups. No significant differences in BP outcomes between groups, however, were found. In conclusion, education by mail was an effective strategy for improving BP control and may be a viable approach for other immigrant groups if the education materials address their cultural needs.