The disproportionate use of medications, combined with age-related pharmacokinetic and pharmacodynamic changes, places older adults at high risk for medication related problems (MRPs). MRPs demonstrate significant morbidity, mortality and economic impact among healthcare systems. The negative outcomes associated with MRPs emphasise the need for more careful and thorough assessments of drug therapy among older adults. In the 1990s a number of methods and instruments were developed to assist in the assessment of medication appropriateness. These tools may be categorised by criteria as: implicit, explicit or one utilising a combination of implicit and explicit criteria. This article reviews these available tools and outlines the advantages and disadvantages of each. In conclusion, those instruments considered to be comprised of both implicit and explicit criteria offer a more thorough assessment of medication appropriateness.