OBJECTIVES: Non-adherence to medication is a barrier to effective treatment of chronic conditions impacting cost, morbidity and mortality. Best practice guidelines recommend that a measure of adherence should be incorporated into pharmacoeconomic submissions, however, this is confounded by a lack of consensus on standardised definitions and appropriate quantitative measurements. We conducted a review to identify the most commonly reported quantitative measures of adherence and those recommended by bodies that produce healthcare guidance and drug regulations. METHODS: A targeted search for systematic reviews of adherence published in 2015 was carried out in EMBASE, MEDLINE and MEDLINE-in-process. Disease specific recommendations were searched for from key organisations which produce healthcare guidance in a selection of chronic diseases; diabetes, rheumatoid arthritis, hepatitis C, HIV and COPD. Materials from the FDA, EMA, CDC, ISPOR and WHO were also screened. RESULTS: