BackgroundPatient-physician communication should be based on plain and simple language. Despite communication skill trainings in undergraduate medical curricula medical students and physicians are often still not aware of using medical jargon when communicating with patients. The aim of this study was to compare linguistic communication skills of undergraduate medical students who voluntarily translate medical documents into plain language with students who do not participate in this voluntary task.MethodsFifty-nine undergraduate medical students participated in this study. Twenty-nine participants were actively involved in voluntarily translating medical documents for real patients into plain language on the online-platform https://washabich.de (WHI group) and 30 participants were not (non-WHI group). The assessment resembled a virtual consultation hour, where participants were connected via skype to six simulated patients (SPs). The SPs assessed participants’ communication skills. All conversations were transcribed and assessed for communication skills and medical correctness by a blinded expert. All participants completed a self-assessment questionnaire on their communication skills.ResultsAcross all raters, the WHI group was assessed significantly (p = .007) better than the non-WHI group regarding the use of plain language. The blinded expert assessed the WHI group significantly (p = .018) better regarding the use of stylistic devices of communication. The SPs would choose participants from the WHI group significantly (p = .041) more frequently as their personal physician. No significant differences between the two groups were observed with respect to the medical correctness of the consultations.ConclusionWritten translation of medical documents is associated with significantly more frequent use of plain language in simulated physician-patient encounters. Similar extracurricular exercises might be a useful tool for medical students to enhance their communication skills with respect to using plain language in physician-patient communication.Electronic supplementary materialThe online version of this article (doi:10.1186/s12909-016-0594-4) contains supplementary material, which is available to authorized users.