Background: Peer assessment has been demonstrated to be an effective educational intervention for health science students. Aims: This study aims to give an overview of all instruments or questionnaires for peer assessments used in medical and allied health professional educational settings and their psychometric characteristics as described in literature. Methods: A systematic literature search was carried out using the electronic databases Pubmed, Embase, ERIC, PsycINFO and Web of Science, including all available inclusion dates up to May 2010. Results: Out of 2899 hits, 28 studies were included, describing 22 different instruments for peer assessment in mainly medical educational settings. Although most studies considered professional behaviour as a main subject of assessment and described peer assessment usually as an assessment tool, great diversity was found in educational settings and application of peer assessment, dimensions or constructs as well as number of items and scoring system per questionnaire, and in psychometric characteristics. Conclusions: Although quite a few instruments of peer assessment have been identified, many questionnaires did not provide sufficient psychometric data. Still, the final choice of an instrument for educational purposes can only be justified by its sufficient reliability and validity as well as the discriminative and evaluative purposes of the assessment.