Objective: There is a need for instruments to assess the Functioning Assessment Short Test practically. In this study the goal was to to perform a reliability and validity analyses of the Functioning Assessment Short Test (FAST) in bipolar disorder. Method: The study was harbored 70 patients with bipolar disorder and 134 healthy control subjects. Thirteen of the patients were in the manic episode, 16 were in the depressive episode, and 41 patients were in remission. First, FAST was translated into Turkish and then it was back-translated into English. The translation was finally approved by the author of the original development study. In the concurrent validity, Bipolar Disorder Functioning Questionnaire (BBi) was used. Results: In the reliability analyses, Cronbach alpha coefficient of internal consistency was calculated to be 0.960, and test-retest reliability coefficient was found to be 0.945. In the validity analyses, in the exploratory factor analysis five factors were obtained and the factor represented social functioning, occupational functioning, autonomy, cognitive functioning and financial issues. In the confirmatory factor analysis, comparative fit index was 0.912 and RMSEA value was 0.085. In the concurrent validity analyses, the domains of FAST were correlated poorly to moderately with the subscales of BBi. FAST discriminated bipolar patients with symptomatic episodes and remitted patients, healthy controls. The area under the ROC curve was found to be 0.824. Conclusion: These results point out that the Turkish version of Functioning Assessment Short Test can used reliably and validly in bipolar patients.