BACKGROUND: Hypertension is common among diabetic patients. The co-existence of two conditions carries an excessive risk of severe complications and mortalities. Limited information exists on the determinants of poor hypertension control among these patients. We aimed at determining the prevalence and factors associated with poor hypertension control in these patients. METHODS: Data of diabetic patients who were also hypertensive attending an outpatient clinic from 1 August 2015 to 31 December 2015 at Bugando Medical Centre were retrospectively analyzed. Uncontrolled hypertension was defined as a blood pressure of ≥130mmHg and/or ≥80mmHg systolic and diastolic respectively. A designed questionnaire was used to collect data of patients. Continuous variables were summarized by median and interquartile ranges (IQR) and categorical variables were summarized by frequency and percentage. Logistic regression was used to find the predictors of uncontrolled hypertension. RESULTS: The majority of our study population were females, 161/295 (54.6%), and the median age was 57 years (IQR 50-64). The prevalence of hypertension was 206/295 (69.8%). A total of 174/206 (84.5%) patients had uncontrolled hypertension. This poor control was significantly associated with poor adherence to anti-hypertensives (OR 1.73[1.26-2.38] p=0.002), presence of any long-term complication (OR 3.19 [1.65-6.18] p=0.03) and overweight (BMI>24.9 Vs <24.9) (OR 1.68 [0.98-2.88], p=0.04). Under-prescription and ambiguous drugs combination was also observed. CONCLUSION: The prevalence of poor hypertension control among diabetic patients in Tanzania is alarming. Most of the factors associated with this situation can be modified. The clinicians should advocate individualized management, continuous health education and adherence to the available guidelines. KEYWORDS: Uncontrolled hypertension diabetes Tanzania