Objective: The medication adherence of patients with chronic physical illnesses is an important aspect of the treatment. However it's difficult to assess the patient's adherence with medication treatment, both because of the difficulty of defining adherence and the patients reluctance for reporting nonadherence. Two different methods are used to evaluate medication adherence which employ clinical measures and self-report measures. Due to the fact that it provides an economical and consistent evaluation, self-report tools are frequently used in the field. Although there are some scales that measure medication adherence in the Turkish literature, the lack of a scale that provides dimensional and generic evaluation is noteworthy. Medication Adherence Report Scale (MARS) is a generic self report scale developed to assess medication adherence in medical treatment. The aim of this study is to examine the Turkish reliability and validity of MARS in patients with chronic physical illnesses.