Background:Procrastination is a common behavior which affects different aspects of life. The procrastination assessment scale-student (PASS) evaluates academic procrastination apropos its frequency and reasons.Objectives:The aims of the present study were to translate, culturally adapt, and validate the Farsi version of the PASS in a sample of Iranian medical students.Patients and Methods:In this cross-sectional study, the PASS was translated into Farsi through the forward-backward method, and its content validity was thereafter assessed by a panel of 10 experts. The Farsi version of the PASS was subsequently distributed among 423 medical students. The internal reliability of the PASS was assessed using Cronbach’s alpha. An exploratory factor analysis (EFA) was conducted on 18 items and then 28 items of the scale to find new models. The construct validity of the scale was assessed using both EFA and confirmatory factor analysis. The predictive validity of the scale was evaluated by calculating the correlation between the academic procrastination scores and the students’ average scores in the previous semester.Results:The corresponding reliability of the first and second parts of the scale was 0.781 and 0.861. An EFA on 18 items of the scale found 4 factors which jointly explained 53.2% of variances: The model was marginally acceptable (root mean square error of approximation [RMSEA] =0.098, standardized root mean square residual [SRMR] =0.076, χ2 /df =4.8, comparative fit index [CFI] =0.83). An EFA on 28 items of the scale found 4 factors which altogether explained 42.62% of variances: The model was acceptable (RMSEA =0.07, SRMR =0.07, χ2/df =2.8, incremental fit index =0.90, CFI =0.90). There was a negative correlation between the procrastination scores and the students’ average scores (r = -0.131, P =0.02).Conclusions:The Farsi version of the PASS is a valid and reliable tool to measure academic procrastination in Iranian undergraduate medical students.