Introduction: We aimed to evaluate the effects of hyperbaric oxygen therapy (HBOT) on erectile function in patients who had no cavernosal or urethral injury by using International Index of Erectile Function (IIEF) questionnaire. Materials and Methods: The male patients who were treated by HBOT for several diseases between July 2017 and September 2017 were examined. All patients filled the IIEF questionnaire form before the first day and after the last day of HBOT and a questionnaire including demographic characteristics and medical history. The effects of demographic characteristics and risk factors on erectile function were evaluated, and the IIEF domain scores of patients in first day and last day of HBOT were compared. Results: Totally, 50 patients were included in the study between July 2017 and September 2017 and the mean age was 59.38 ± 13.77. The mean post-HBOT IIEF-EF score of patients was significantly higher than the mean pre-HBOT IIEF-EF score of patients (15.74 ± 10.52 vs. 19.50 ± 10.91; p < 0.001). The mean post-HBOT IIEF scores of other domains including intercourse satisfaction, orgasmic function, sexual desire, and overall satisfaction were also significantly higher than pre-HBOT scores. Conclusions: HBOT may be a good alternative treatment or adjunctive treatment for erectile dysfunction.