Aim: To develop a standardized framework determining the economic impact of medication nonadherence. Materials & methods: Secondary analysis of existing literature reported cost data, aggregating cost outcome indicators. Weighted-average cost analysis performed, determining the proportional contribution to total cost. Results: Direct costs were reported in 92% of studies and indirect costs in 4% of studies. Three most utilized cost categories were hospital (68%), primary care (18%) and pharmacy costs (72%). Average unadjusted direct costs ranged from $625 to $154,203 contributing to 88% of the total cost; adjusted medical costs ranged from $565 to $56,313 representing 96% of the total cost. Conclusion: The medication adherence cost estimation framework enables the comparison of costing studies, facilitating informed health policy decision-making based on consistent evidence and terminology.@en