A recent meta-analysis in this journal showed incidences between 3.4 and 33.9%. Studies performed by pharmacists and epidemiologists produced lower incidences than internists' studies. We reassessed the prevalence of iatrogenic admissions in a study of internists. Iatrogenic disease was defined as adverse drug reactions according to the World Health Organization Definition and complications induced by non-drug medical interventions. Subsequent admissions at the Departments of Medicine/Cardiology/Pulmonology in a 1,250 bed general hospital in the Netherlands from May 2007 to August 2007 were studied. 2,000 consecutive admissions were studied: 576 (29%, 26-32%) were classified as possibly iatrogenic; out of these 380 (19%, 17-22%) as definitely iatrogenic, out of whom 229 (12%, 10-14%) had already been classified as iatrogenic by the admitting physicians. Patients with cardiac disease, hypertension, gastrointestinal conditions, anticoagulant treatment and use of NSAIDs were, particularly, at risk of iatrogenic admission with percentages of 22 (16-24), 13 (11-18), 12 (9-15), and 7 (5-11) %. An independent predictor of iatrogenic admissions was age with an odds ratio of 1.27 per 10 years (p = 0.0001). 1. At least 19% of admissions to the Departments of Internal Medicine/Cardiology/Pulmonology, and, maybe, even percentages up to 29% were due to adverse drug effects. 2. A large difference between the numbers of iatrogenic admission according to the physicians in charge of admission and the investigators, 229 versus 380 patients, was observed. 3. Most often iatrogenic admissions were observed with cardiac disease, hypertension, gastrointestinal conditions, anticoagulant treatment, and use of NSAIDs.