['To investigate the reliability of the physician-assisted International Index of Erectile Function (IIEF).', '374 patients who applied to our clinic with erectile dysfunction problems were asked to complete the IIEF questionnaire; 225 patients who visited the clinic again within 1-3 days completed the IIEF questionnaire again. All questions were answered by the patients themselves. At both visits, necessary explanations were provided by the physician to patients who requested assistance. Data obtained from the first and second questionnaires were compared.', "There was a significant difference between the first and second questionnaires with respect to certain questions. Nevertheless, no significant difference was found between the IIEF.1 and IIEF.2 scores (p > 0.20) for the group overall or for any subgroups. The test-retest correlation coefficients for all patients were highly significant (r = 0.909, p < 0.01). A high degree of internal consistency was observed for each of the first and second physician-assisted IIEF questionnaires (Cronbach's α 0.926 and 0.908, respectively, p < 0.001)."] Is despite some comprehension problems the International Index of Erectile Function a reliable questionnaire in erectile dysfunction?