We examined the efficacy of candesartan in reducing cardiovascular events in hypertensive patients with coexisting chronic kidney disease and cardiovascular diseases. This open-label, prospective study was conducted from 1999 to 2002, and 141 hypertensive subjects 60 to 75 years old with non-diabetic chronic renal insufficiency were enrolled. Before randomization of the patients, we examined their past medical history and found that 69 patients had been hospitalized due to myocardial infarction (MI) or stroke. Therefore, the patients were divided into 2 groups, one with previous histories of MI or stroke and the other with no previous history of Ml or stroke. The patients were randomized to receive either the angiotensin receptor blocker candesartan or conventional treatment. The mean duration of follow-up was 3.1 +/- 0.4 years. The primary outcome was a primary cardiovascular event (MI, stroke, or heart failure) verified by hospitalization. At the end of the study, in the patients with past history of cardiovascular diseases, blood pressure was reduced from 146.4 +/- 7.2/79.2 +/- 5.1 to 34.4 +/- 6.1/72.3 +/- 4.0 mmHg in the candesartan group and from 145.3 +/- 5.1/80.1 +/- 3.8 to 133.4 +/- 5.8/73.8 +/- 4.2 mmHg in the conventional treatment group. In the patients without past history of cardiovascular diseases, blood pressure was reduced from 143.2 +/- 4.3/78.3 +/- 4.8 to 133.8 +/- 5.3/ 73.1 +/- 3.8 mmHg in the candesartan group and from 143.9 +/- 6.8/78.1 +/- 4.2 to 132.6 +/- 5.4/74.5 +/- 4.4 mmHg in the conventional treatment group at the end of the study. There were no significant differences between the candesartan group and the conventional treatment group in the reduction of blood pressures. Among patients with a past history of cardiovascular disease, the serum creatinine concentration increased from 1.49 +/- 0.38 to 1.58 +/- 0.42 by candesartan treatment and from 1.50 +/- 0.32 to 1.89 +/- 0.37 by conventional treatment. On the other hand, in patients with no past history of cardiovascular disease, the serum creatinine concentration increased from 1.44 +/- 0.42 to 1.46 +/- 0.40 by candesartan treatment and from 1.46 +/- 0.44 to 1.51 +/- 0.38 by conventional treatment. Although, there was no significant difference in the incidence of cardiovascular events between the 2 groups with the candesartan-based and conventional-based antihypertensive treatment, in patients without cardiovascular events (12/36 vs. 7/34: these figures indicate events per total participated persons per 3 years; following figures are the same as this), treatment with candesartan reduced the incidence of cardiovascular events in the patients with past history of cardiovascular diseases (20/33 vs. 32/ 38). In particular, candesartan-based treatment reduced the incidence of congestive heart failure by 66.4% in these patients. In conclusion, this prospective, open-labeled randomized study suggests that 1) previous history of cardiovascular diseases is a major risk factor for cardiovascular events; and 2) candesartan is effective for reduction of cardiovascular events in hypertensive patients with coexisting chronic kidney disease and cardiovascular diseases, especially for prevention of congestive heart failure.