Albuminuria has been shown to identify patients with an increased cardiovascular risk, and in clinical studies ACE inhibitors reduce the urinary protein excretion. It was the primary aim of this intensified monitoring project to determine whether these results can be reproduced in a clinical practice setting. Micro- (2.7–22.6 mg albumin/mmol creatinine) or macroalbuminuria (>22.6 mg/mmol) was confirmed by a central laboratory in 598 out of 773 patients with hypertension who had albuminuria >50 mg/l on a Micral Test<sup>®</sup> II performed by 147 general practitioners. Coronary heart disease (prevalence rates 15% in patients with normalbuminuria, 33% in patients with microalbuminuria, and 40% in patients with macroalbuminuria), heart failure (prevalence rates 19, 29, and 32%, respectively), left ventricular hypertrophy (prevalence rates 30, 42, and 38%, respectively), and peripheral vascular disease (prevalence rates 7, 15, and 20%, respectively) were significantly more common in patients with elevated urinary albumin excretion. 230 patients with microalbuminuria and 202 subjects with macroalbuminuria were treated with the angiotensin-converting enzyme inhibitor ramipril for 6 months. The treatment significantly lowered mean arterial blood pressure (from a median value of 120 mm Hg, quartiles 113–125 mm Hg, to 103 mm Hg, quartiles 100–109 mm Hg) as well as urinary albumin excretion (from a median value of 18 mg/mmol creatinine, quartiles 7.2–54.6 mg/mmol creatinine, to 6.5 mg/mmol creatinine, quartiles 1.6–23.1 mg/mmol creatinine). The treatment efficacy was unaffected by age, body mass index, and smoking status. Patients with diabetes mellitus type II and heart failure also had a significant, although less pronounced reduction of albuminuria. In summary, we conclude that ramipril is able to reduce the urinary albumin excretion in a clinical practice setting, as has been shown in clinical studies. However, the treatment response is not completely uniform, as special patient populations seem to be more resistant to therapy.