Previous studies have shown that oxidative stress and corporal fibrosis in penile tissues of rats were key pathological factors of erectile dysfunction induced by diabetic mellitus (DMED). Lipoxin A4 (LXA4) was reported to inhibit oxidative stress and fibrosis diseases, while whether it could exert a protective role on erectile function was not clear. Type I diabetic mellitus (DM) was induced in thirty male 10-week-old Sprague-Dawley rats using streptozotocin. Ten weeks later, twenty-two rats with DMED confirmed by an apomorphine test were divided into two groups: The DMED group (n = 11) and the DMED + LXA4 group (n = 11; LXA4 injection daily for 4 weeks). In addition, another ten age-matched rats formed the Control group. We found that erectile function was significantly impaired in the DMED group compared with the Control group, but was improved in the DMED + LXA4 group. Similarly, the over-activated oxidative stress and impaired endothelial function in the DMED group were both improved in the DMED + LXA4 group. Moreover, the DMED group showed serious corporal fibrosis, which was also inhibited by the treatment of LXA4 in the DMED + LXA4 group. Taken together, LXA4 could exert an inhibition role on oxidative stress and fibrosis to improve DMED effectively. © 2018 The Author.