This study evaluates the psychometric properties and concurrent and predictive validity of an 8-item self-reported medication adherence measure in patients with hypertension. The measure was found to be reliable (Cronbach's alpha = 0.83) and significantly associated with blood pressure control. Using a cutpoint of <6, the measure had a sensitivity of 93% and specificity of 53% in identifying patients with poor blood pressure control. The measure showed good concurrent and predictive validity in low-income patients with hypertension, suggesting it could serve as a useful screening tool in outpatient settings. Hypertension is a major risk factor for cardiovascular disease and remains a significant public health challenge. Despite effective treatments, only 2% of hypertensive patients in a 2004-2005 survey had controlled blood pressure. Patient adherence to prescribed therapies is a key factor in blood pressure control, with adherence being associated with better outcomes. Factors influencing adherence include knowledge, social support, stress, and treatment satisfaction. The study involved 1367 patients, with a mean age of 52.5 years, 40.8% male, 76.5% Black, and 54.1% with income < $5,000. The 8-item adherence scale was significantly correlated with a previously validated 4-item scale (Pearson correlation = 0.64, P < 0.05). Confirmatory factor analysis confirmed the scale was unidimensional. The scale was effective in identifying patients with poor adherence, with 32.1% classified as low adherers, 52.0% as medium adherers, and 15.9% as high adherers. Patients with higher adherence scores were more likely to have controlled blood pressure. In a multivariate model, knowledge, patient satisfaction, coping, stress, and medication complexity were significantly associated with adherence. The study highlights the importance of assessing medication adherence in clinical settings. While self-report measures may be subject to bias, they are simple, cost-effective, and can provide real-time feedback on adherence behavior. The 8-item scale showed higher sensitivity than the original 4-item scale and could be useful in identifying patients at risk for uncontrolled blood pressure. The study also discusses the limitations of the research, including the focus on low-income minority patients and the need for further validation in other populations. The findings suggest that the 8-item adherence scale is a practical tool for identifying adherence issues and monitoring treatment outcomes in clinical settings.This study evaluates the psychometric properties and concurrent and predictive validity of an 8-item self-reported medication adherence measure in patients with hypertension. The measure was found to be reliable (Cronbach's alpha = 0.83) and significantly associated with blood pressure control. Using a cutpoint of <6, the measure had a sensitivity of 93% and specificity of 53% in identifying patients with poor blood pressure control. The measure showed good concurrent and predictive validity in low-income patients with hypertension, suggesting it could serve as a useful screening tool in outpatient settings. Hypertension is a major risk factor for cardiovascular disease and remains a significant public health challenge. Despite effective treatments, only 2% of hypertensive patients in a 2004-2005 survey had controlled blood pressure. Patient adherence to prescribed therapies is a key factor in blood pressure control, with adherence being associated with better outcomes. Factors influencing adherence include knowledge, social support, stress, and treatment satisfaction. The study involved 1367 patients, with a mean age of 52.5 years, 40.8% male, 76.5% Black, and 54.1% with income < $5,000. The 8-item adherence scale was significantly correlated with a previously validated 4-item scale (Pearson correlation = 0.64, P < 0.05). Confirmatory factor analysis confirmed the scale was unidimensional. The scale was effective in identifying patients with poor adherence, with 32.1% classified as low adherers, 52.0% as medium adherers, and 15.9% as high adherers. Patients with higher adherence scores were more likely to have controlled blood pressure. In a multivariate model, knowledge, patient satisfaction, coping, stress, and medication complexity were significantly associated with adherence. The study highlights the importance of assessing medication adherence in clinical settings. While self-report measures may be subject to bias, they are simple, cost-effective, and can provide real-time feedback on adherence behavior. The 8-item scale showed higher sensitivity than the original 4-item scale and could be useful in identifying patients at risk for uncontrolled blood pressure. The study also discusses the limitations of the research, including the focus on low-income minority patients and the need for further validation in other populations. The findings suggest that the 8-item adherence scale is a practical tool for identifying adherence issues and monitoring treatment outcomes in clinical settings.