Objective: To compare blood pressure (BP) control in patients receiving irbesartan/hydrochlorothiazide (HCTZ) and valsartan/HCTZ at a tertiary care university hospital in Oman. Subjects and Methods: This was a retrospective observational study, where 232 patients' medical records were reviewed during a 3-month period, July to September 2010, at Sultan Qaboos University Hospital in Oman. BP readings of the previous 6 months were also retrieved from the electronic medical records. Analyses were conducted using univariate statistical techniques. Results: The mean age of the cohort was 58 ± 11 years (range: 21-88). Sixty-nine (30%) patients were on the irbesartan/HCTZ combination (150/12.5 mg) and 163 (70%) were on the valsartan/HCTZ combination. The patients on the valsartan/HCTZ combination were divided into two subgroups: 117 (72%) received 160/12.5 mg and 46 (28%) 80/12.5 mg. Diabetic patients (43/69, 62%, vs. 61/163, 37%, p < 0.001) and those with diabetic nephropathy (8/69, 12%, vs. 7/163, 4%, p = 0.039) were prescribed more often irbesartan/HCTZ than valsartan/HCTZ. In comparison to the valsartan/HCTZ cohort, the irbesartan/HCTZ group was associated with significant reductions in both systolic BP (SBP; -9 vs. -2 mm Hg; p = 0.021) and diastolic BP (DBP; -5 vs. 0 mm Hg; p = 0.022). BP reductions were noted more in diabetics than nondiabetics with the irbesartan/HCTZ patients associated with significant reductions in both SBP (-12 vs. 5.1 mm Hg; p < 0.001) and DBP (-6.4 vs. 1.9 mm Hg; p = 0.001). Conclusions: The irbesartan/HCTZ combination was associated with significant reductions in both SBP and DBP when compared with the valsartan/HCTZ combination. Specifically, the reductions were noted more in diabetics than nondiabetics.