OBJECTIVES: Under the pressure of fiscal consolidation and pharmaceutical spending decrease in Greece, mandatory generic substitution and compulsory prescription by international non-proprietary name (INN)were recently introduced as reimbursement drivers in Greece. This study aims to investigate the implications of INN implementation regarding chronic patients’ choices and their willingness to switch to an alternative pharmaceutical treatment. METHODS: A cross-sectional study was carried out among 1600 patients from four chronic disease groups(HTN, Diabetes,COPD and Alzheimer). Logistic regression analysis was used to investigate the factors associated with chronic patients’ choices. RESULTS: Out of 1600 patients approached, 1594responded to the survey(99.6%). 69% of them stated that they were aware of the new reimbursement system. After the implementation of INN prescribing, only few(11%) have changed their usual drug. 43% were totally certain that an original drug is more effective than a generic, while 67% have never used generics in the past. Most patients(82%) preferred to be prescribed their usual medicine, despite of the extra cost they had to bear. This choice was a co-decision with their physician as 58% of them stated.  The average additional amount that they would be willing to spend in order not to switch to another medicine was estimated at €17.8. These results showed a significant statistical correlation with patients’ income, educational level and occupation category. CONCLUSIONS: According to this study chronic patients are not willing to change their usual drug and switch to a generic, despite the cost this choice imposes. Consequently INN prescribing may decrease public expenditures on pharmaceuticals but it will lead to higher private expenditure. Given that due to economic crisis incomes are continuously decreasing  and unemployment rate is rising, the measure might eventually result in lower adherence to medication and consequently in adverse effects on patients health status and future public expenditure for treating possible complications.