In this paper the data on the duplicate use of ACE inhibitors among a community-dwelling elderly population are presented. Using a questionnaire, 1000 subjects were interviewed concerning the use of drugs, 654 females, mean+/-SD age: 72.6+/-6.5 years. They were divided into two groups: Group A (5%) taking at least two ACE inhibitors (n=50) and Group B: those who used either a single ACE inhibitor or no ACE inhibitor (n=950). In Group A, 49 individuals were taking two different ACE inhibitors concomitantly and one was using three. The most commonly used ACE inhibitor was enalapril (29 of 50 subjects). Subjects in Group A consumed significantly more drugs, both of prescription (Rx) and nonprescription (OTC), compared to those in Group B (total means: 8.4+/-2.8 vs. 6.7+/-3.2; p<0.01, Rx means: 6.3+/-2.5 vs. 5.2+/-2.8, p<0.05, OTC means: 2.0+/-1.6 vs. 1.6+/-1.5, p<0.05). Also, they were more likely to have consulted a cardiologist (17/50 vs. 201/950, p<0.05). The duplicate use of ACE inhibitors in 5% of a population of community-dwelling elderly patients seems to be caused by both poor doctor-doctor communication and polypharmacy. This phenomenon could possibly be dangerous especially when potential additive adverse effects are taken into account.