As part of the Edgecombe County High Blood Pressure Control Program, we conducted a medical record review within a private group practice to assess the interrelationships between patient characteristics, the process of medical care, and dropping out of care by hypertensive patients. Twenty-one percent of 641 randomly selected hypertensive patients did not have a clinic visit in the year before their record review date. Loss to follow-up varied from 31% for black men to 13% for white women. More intense prior contact with the medical care system was associated with remaining under medical care for all groups by race and sex. Black men were much less likely to have intense contact with the medical care system than the other groups. Physician aggressiveness in the use of drug therapy was associated with a nearly 40% reduction in the risk of being lost to follow-up. These findings suggest that patient characteristics and several factors that reflect the process of medical care are associated with dropping out of medical care by hypertensive patients.