Analysis of the global burden of hypertension revealed that over 26% of the world's adult population had hypertension in 2000 [7,10], and has shown a rapid increase in prevalence affecting significant numbers of individuals in Sub-Saharan Africa. Although there is AbstractHypertension is an important worldwide public-health challenge because of its high frequency and risk factor for cerebrovascular, cardiovascular and kidney disease. Drug therapy problems are a significant challenge to health care providers. It severely compromises the effectiveness of treatment making this a critical issue in population health both from the perspective of quality of life and of health economics. Therefore, the objective of this study is to determine the pattern and magnitude of drug therapy problems in the study hospital and to find out risk factors for these problems. The study was questionnaire-based Cross sectional design which was conducted from April to May 2014 at Adama Hospital Medical College. A convenient sampling method was used and a total of 192 hypertensive patients were included in the study. Data were analyzed using SPSS software program. In this study 155 (80.7%) patients have at least one drug therapy problem and a total of 452 drug therapy problems were identified in them. The most common drug therapy problem identified in this study was drug interaction (n=259, 58.7%), followed by non-adherence and adverse drug interaction constituting 19.5% and 18.6% respectively. Under dose accounts only 0.9% of all drug therapy identified. Marital status, number of drugs and number of co morbidities significantly affect drug therapy problems. The study showed that 80.7% of the patients in the study have drug therapy problems. Number of complications and number of drugs significantly affect drug therapy problems. Therefore, patients with multiple diagnosis and patients using multiple drugs should be closely monitored for drug therapy problem, to avoid clinically significant harmful consequences.