Purpose: Emergency physicians refer to primary care for follow-up of conditions identified in the emergency department (ED). Hypertension is a major risk factor for cardiovascular disease. Its detection is key in decreasing morbidity and mortality. We examined factors associated with diagnosing possible hypertension in patients with high blood pressure (BP), as a first step in outpatient referral. Methods: Data from a national ED survey were examined for visits by adults with high BP. The dependent variable was a hypertension diagnosis. Independent variables were BP elevation stage, age, sex, ethnicity, payment, year, pain severity, and urban versus rural location. Bivariate associations were tested between all independent variables and a diagnosis of possible hypertension. Logistic regression models determined significant predictors of a hypertension diagnosis. Results: Only 5.5 percent of ED patients with high BP were diagnosed with hypertension. Predictors included stage 2 BP elevation, age over 30 years old, females, minority ethnic groups, and mild or no pain. Conclusions: This analysis suggests associated factors influencing the diagnosis of hypertension in the ED to facilitate referral, which can have significant benefits in reducing complications of untreated hypertension.