Several different investigators have reported increased stroke mortality in the southeastern United States, leading to the introduction of the term "Stroke Belt." The results presented here from the Veterans Administration Hypertension Screening and Treatment Program (HSTP) demonstrate an increased all-cause mortality among hypertensive patients seen in HSTP clinics in the southeastern United States when compared with similar patients from other HSTP clinics. Several different groupings of southeastern states were examined and compared with nine states west of the Mississippi River. A total of 11,936 male veterans, 5737 of whom were black, were identified as hypertensive during 1974-1976 in 32 HSTP clinics. Their mean age was 52.4 +/- 10.4 years, and their mean pretreatment blood pressure was 153.8 +/- 19.1/100.4 +/- 9.8 mm Hg. During a minimum of 13.9 years of follow-up, 5360 (44.9%) of these patients died. Proportional hazards modeling was used to fit a basic survival model with terms representing race, age, blood pressure, smoking, and obesity. Risk was increased with higher blood pressure, age, and smoking and with lower body mass index. For 6 HSTP clinics in an 11-state Stroke Belt (defined as states with stroke mortality > 10% above the United States average), the relative risk of death was 1.226 (95% confidence interval, 1.106-1.358) when compared with 9 states west of the Mississippi River. For two different groupings of southeastern states with 10 and 8 HSTP clinics the relative risk of death was 1.231 and 1.295.(ABSTRACT TRUNCATED AT 250 WORDS)