It is well established that information on their disease is one of the prerequisites for improvement of patients' compliance with therapy. The authors have therefore developed a simple slide program presenting information on hypertension and obesity. Consisting of 52 slides, it was shown in the central waiting room of the medical outpatient department at the University Hospital, Zurich. In order to assess learning, 841 patients were asked to fill in a questionnaire. 485 had seen the program and 356 served as controls with the program switched off. Four main results emerged: 1. The percentage of subjects scoring greater than or equal to 4 correct answers (of a maximum of 5) rose significantly from 22.6% to 64.2%. 2. The number of incorrect answers (maximum 3) remained unchanged. 3. Learning decreased with age. 4. Occupation did not have a significant effect on learning. The results clearly show that the program represents an effective method of teaching patients and may therefore serve to improve compliance with therapy.