Blood pressure (BP) control is a key intervention to decrease cardiovascular diseases (CVD), the main cause of death in low and middle-income countries (MIC). Scarce data on the determinants of BP control in Latin America are available. Our objective is to explore the role of gender, age, education, and income as social determinants of BP control in Argentina, a MIC with a universal health care system. We evaluated 1184 persons in two hospitals. Blood pressure was measured using automatic oscillometric devices. We selected those patients treated for hypertension. The average BP of less than 140/90 mmHg was considered a controlled BP. We found 638 hypertensive individuals, of whom 477 (75%) were receiving antihypertensive drugs, and of those, 248 (52%) had controlled BP. The prevalence of low education was more frequent in uncontrolled patients (25.3% vs. 16.1%; P < .01). We did not find association between household income, gender, and BP control. Older patients had less BP control (44% of those older than 75 years vs. 60.9% of those younger than 40; test for trend P < .05). Multivariate regression indicates low education (OR 1.71 95% CI [1.05, 2.79]; P = .03) and older age (OR 1.01; 95% IC [1.00, 1.03]) as independent predictors of the lack of BP control. We conclude that rates of BP control are low in Argentina. In a MIC with a universal health care system low education and old age but not household income are independent predictors of the lack of BP control.