BACKGROUND: Criteria to assess the appropriateness of prescriptions might serve as a helpful guideline during professional training and in daily practice, with the aim to improve a patient's pharmacotherapy. OBJECTIVE: To create a comprehensive and structured overview of existing tools to assess inappropriate prescribing. METHOD: Systematic literature search in Pubmed (1991-2013). The following properties of the tools were extracted and mapped in a structured way: approach (explicit, implicit), development method (consensus technique, expert panel, literature based), focused patient group, health care setting, and covered aspects of inappropriate prescribing. RESULTS: The literature search resulted in 46 tools to assess inappropriate prescribing.Twenty-eight (61%) of 46 tools were explicit, 8 (17%) were implicit and 10 (22%) used a mixed approach. Thirty-six (78%) tools named older people as target patients and 10 (22%) tools did not specify the target age group. Four (8.5%) tools were designed to detect inappropriate prescribing in hospitalised patients, 9 (19.5%) focused on patients in ambulatory care and 6 (13%) were developed for use in long-term care. Twenty-seven (59%) tools did not specify the health care setting. Consensus methods were applied in the development of 19 tools (41%), the others were based on either simple expert panels (13; 28%) or on a literature search (11; 24%). For three tools (7%) the development method was not described. CONCLUSION: This overview reveals the characteristics of 46 assessment tools and can serve as a summary to assist readers in choosing a tool, either for research purposes or for daily practice use.