Objectives: The objectives of this study were to identify: perceptions regarding underuse and characteristics of generic medicines; patients' attitudes towards drug substitution and pharmacists' attitudes towards substitution recommendation.

Methods: Two questionnaires were designed and interviewer-administered - one to patients and another to pharmacists.  A binary variable ‘correct understanding’ was created and multiple logistic regression analysis was used to identify factors associated with experience and willingness to accept generic medicine substitution.  Statistical analyses were performed by SPSS version 19.0.

Results: All of the 417 patients knew the term 'generic medicine'.  Level of education, experience and discussion with doctor were significantly associated with correct understanding. 77.5% of respondents had consumed generic medicines and 88.7% (64.5%) were willing to accept drug substitution based on doctor's (pharmacist's) recommendation.  Having at least one chronic condition, discussion with doctor and perception that generic drug substitution is cost-saving were significantly associated with experience.  In addition to the last two, having correct understanding and having experience were significantly associated with willingness to accept generic drug substitution.  91.6% of pharmacists (95 respondents) said that drug substitution is recommended in their pharmacies.

Conclusions: More information should be given to patients preferably by doctors and pharmacists.  Prescribing should be encouraged and experience promoted.