Both depression and hypertension (HTN) are prevalent, costly, and destructive, and frequently coexist among the aging population of China. This study aimed to examine the role that treatment adherence plays in blood pressure control in older adult Chinese with depression. Data for these analyses were taken from a randomized control trial of a collaborative depression care management intervention conducted in rural villages of Zhejiang Province, China with older adults who had comorbid depression and HTN. They included baseline assessments of 2362 subjects ages ≥60years, whose blood pressure and depression were measured using a calibrated manual sphygmomanometer and the Chinese version of the 17-item Hamilton Depression Rating Scale (HDRS-17), respectively. Treatment adherence was identified by a single question asking whether patients on occasion did not take their medicine. Uncontrolled HTN was associated with older age (t=3.10, P<0.01), higher HDRS-17 score (t=5.76, P<0.01), and higher rates of non-adherence to HTN treatment (χ2 =21.34, P<0.01). Logistic regression models indicated that adherence accounted for 39.4% of the total effect between depression and HTN. Specifically, those with poor adherence were at 1.417 greater odds of having their HTN uncontrolled compared with those with good adherence. Hypertension control in older adults with depression is complicated by nonadherence to treatment. In addition to diagnosing and treating depression in their older adult patients, primary care physicians can optimize blood pressure control by identifying and addressing their patients' adherence to recommendations for HTN management.