Objectives: Angiotensin Receptor Blockers such as Valsartan, are a newer class of drugs associated with significant reductions in cardiovascular morbidity and mortality. They are commonly used in hypertension, chronic heart failure, diabetes-related nephropathy and post-myocardial infarction in patients who are intolerant to Angiotensin Converting Enzyme inhibitors (ACEi). A review of medicines used in Royal Hospital (an Omani tertiary health care centre) during 2004 and 2005 showed that Valsartan was one of 20 most expensive drugs used. The main objective of this study was to evaluate the pattern of prescribing valsartan in out-patient clinics. Methods: a retrospective study, applying medicines use evaluation, to describe the pattern of prescribing Valsartan in comparison with international guidelines. The study carried out in the outpatient pharmacy setting, Royal Hospital from 15th May to 30th June 2006. It included 120 adult patients who had been prescribed Valsartan at the outpatient clinics during the study period. Results: among the 120 patients only 109 patients were finally included in the study. Elevenpatients who had had duplicated prescriptionswere excluded from the study. 78% of the patients were on Valsartan for its FDA-approved indications while 22% of patients were for other non-approved indications. Half of the patients were initiated on an ACEi before shifting to Valsartan. The other half of the patients was started with Valsartan as a first line choice without any clinical justification. Conclusion: The study showed that half of the patients were initiated on Valsartan without being prescribed an ACEi prior to that, while the recommendation in most of the international guidelines based on indication stated that ARBs are used in patients who are intolerant to ACEi. The study emphasizes the need for further research to highlight the need for developing national guidelines and adhering to these guidelines for rational prescribing.