Unlabelled: To assess and quantify the impact of the literature in diagnostic decisions and treatment of patients admitted to an internal medicine service using the methodology of evidence-based medicine. From November 2012 to February 2013, patients who were hospitalised in the internal medicine service of Regional Hospital of Lugano (Switzerland) and generated questions on medical care were randomly assigned to two groups: an 'intervention group' (supported by the literature research) and a 'control group' (not supported by the literature research). The information obtained from the literature was submitted by email to all members of the medical team within 12 h after asking the question. Two hundred and one participants, from 866 patients hospitalised in the analysed period, divided into intervention (n=101) and control (n=100) groups, generated questions. In the intervention group, bibliographical research was possible for 98 participants. The medical team accepted the results and implemented the research for 90.8% of these participants (89/98). Statistical analyses were carried out on the intention-to-treat and on the per-protocol populations. Bibliographical research had a significant protective effect on transfer to an intensive care unit (relative risk (RR)=0.30; 95% CI 0.10 to 0.90; χ²=5.3, p=0.02) and hospital readmissions were also influenced by bibliographical research (RR=0.42; 95% CI 0.17 to 1.0; χ²=3.36, p=0.05) in the intention-to-treat population. Our results point out the importance of bibliographical support on the quality of medical care. In particular, they show its possible impact on clinical outcome., Trial Registration Number: EOC Registry (registration number: 14-055).