This study sought to assess blood pressure (BP) control rates by determining the factors associated with poor BP control, therapeutic management and physicians' therapeutic behavior among elderly Spanish hypertensive patients in a primary care setting. This cross-sectional multicenter study included hypertensive patients at least 80 years of age in primary care settings throughout Spain who were on pharmacologic treatment. BP was considered well controlled at <140/90 mm Hg (<130/80 in patients with diabetes, chronic renal disease or cardiovascular disease). A total of 923 patients were included (83.3+/-3.5 years; 62.9% women). Almost two-thirds (64.0%) of the patients were taking a combined therapy (68.7%; 2 drugs) and approximately one-third (35.6%; 95% CI 32.6-38.7) of the patients attained BP goals. Physicians modified the antihypertensive treatment in 26.1% (95% CI 22.3-29.9) of patients with uncontrolled BP, which most frequently involved the addition of another drug (47.6%). Predictive factors for no BP control and no therapeutic modification in patients with uncontrolled BP included diabetes (OR 2.8 (95% CI 2.0-3.9); P<0.0001) and mistaken physician perceptions about BP control (OR 108.1 (95% CI 40.5-288.6); P<0.0001), respectively. Only three out of 10 hypertensive patients 80 years or older in Spain achieved the BP goals. Physicians only modified the treatment in one out of four patients with uncontrolled BP. Diabetes was associated with a threefold increase in the likelihood of uncontrolled BP, and the mistaken physician perceptions about BP control were associated with a 100-fold rise in the probability of not modifying antihypertensive therapy.