OBJECTIVESTo analyse the control rate of irbesartan/hydrochlorothiazide (HCTZ) combination tablets (COAPROVEL) in the treatment of patients with mild to moderate primary hypertension.METHODSIn this multi-center, open, single therapy trial, the enrolled patients aged 18-75 were treated with irbesartan/HCTZ combination tablets for 8 weeks. The initial dose comprised one tablet of irbesartan (150 mg)/HCTZ (12.5 mg) once a day during the first 2 weeks. If diastolic blood pressure was greater than 85 mm Hg at the end of the second or fourth weeks, irbesartan (300 mg)/HCTZ (12.5 mg) once a day or irbesartan (300 mg)/HCTZ (25 mg) once a day were added respectively.RESULTSIn 968 patients with mild to moderate hypertension enrolled, 920 patients were followed up for 8 weeks. (1) After 1 week of treatment, irbesartan/HCTZ combination tablets lowered systolic blood pressure by 11.87 mm Hg and diastolic blood pressure by 8.54 mm Hg (P < 0.01). After 8 weeks of treatment, the corresponding decreases were 21.97 mm Hg and 16.08 mm Hg, respectively (P < 0.01). (2) After 2, 4 and 8 weeks of treatment, 526, 703 and 769 patients reached blood pressure target (diastolic blood pressure less than 85 mm Hg). The control rates were 57.17%, 76.41% and 83.59%, respectively. (3) Among the 920 patients who completed the trial, 637 patients took irbesartan (150 mg)/HCTZ (12.5mg) once a day (69.24%), 211 patients took irbesartan (300 mg)/HCTZ (12.5 mg) once a day (22.93%), and 72 patients took irbesartan (300 mg)/HCTZ (25 mg) once a day (7.82%). (4) In the intention-to-treat analysis, no adverse reaction was observed in 903 patients (93.29% of the patients enrolled).CONCLUSIONSWhen irbesartan/HCTZ combination regimen are used in the treatment of patients with mild to moderate primary hypertension, the proportion of patients reaching blood pressure target is high and adverse reactions are rare.