Background: A negative attitude toward treatment is a major obstacle to treat bipolar disorder. Objectives: The current study aimed at assessing the reliability and validity of Persian version of drug attitude inventory (DAI-10) in patients with bipolar I disorder and finding its relationship with patients' compliance in order to predict the disorder. Methods: To assess test-retest reliability, 30 outpatients with bipolar I disorder were selected. They were asked to answer the questions at the onset of the study and four to ten days later. Then, the relationship between DAI-10 scores of 82 patients in bipolar disorder patients' follow-up (BDPF) study, and medication possession ratio (MPR) were investigated. The patients were divided into poor and good compliance, and cut off point of the tool was assigned. Positive and negative predictive value of DAI score was also calculated.