Electronic disease registries are a critical feature of the chronic disease management programs that are used to improve the care of individuals with chronic illnesses. These registries have been developed primarily in managed care settings; use in safety net institutions-organizations whose mission is to serve the uninsured and underserved-has not been described. We sought to assess the feasibility of developing disease registries from electronic data in a safety net institution, focusing on hypertension because of its importance in minority populations. We compared diagnoses obtained from algorithms utilizing electronic data, including laboratory and pharmacy records, against diagnoses derived from chart review. We found good concordance between diagnoses identified from electronic data and those identified by chart review, suggesting that registries of patients with chronic diseases can be developed outside the setting of closed panel managed care organizations.