A randomized controlled trial was performed between June and December 1989 in 379 outpatients to evaluate whether a patient information booklet is able to reduce anxiety levels before gastroscopy or colonoscopy. Anxiety levels were measured by a Visual Analogue Scale (VAS) in all patients entering the office. Half of the patients received the information booklet about the endoscopic investigations and half did not. VAS was measured again directly before endoscopy in each patient. All patient groups were comparable. The median anxiety level of gastroscopy patients before and after reading the information booklet was 5.3 (2.5-10) and 4.9 (0.8-10), and for colonoscopy patients 6.0 (2.5-10) vs 5.0 (0.7-10). So not much difference concerning the anxiety level before and after reading the patient information booklet was found. Thus better than an information booklet, for every patient an individualized technique of the endoscopist may reduce patient anxiety before gastroscopy or colonoscopy.