Introduction: For patients with diabetes, erectile dysfunction (ED) is common and greatly affects quality of life. However, these patients often exhibit a poor response to first-line oral phosphodiesterase type 5 inhibitors. Aim: To investigate whether taurine, a sulfur-containing amino acid, affects diabetic ED (DED). Methods: Type 1 diabetes mellitus was induced in male rats by using streptozotocin. After 12 weeks, an apomorphine test was conducted to confirm DED. Only rats with DED were administered taurine or vehicle for 4 weeks. Age-matched nondiabetic rats were administered saline intraperitoneally for 4 weeks. Main Outcome Measures: Erectile function was evaluated by electrical stimulation of the cavernous nerve. Histologic and molecular alterations of the corpus cavernosum also were analyzed. Results: Erectile function was significantly reduced in the diabetic rats compared with in the nondiabetic rats, and was improved in the diabetic rats treated with taurine. The corpus cavernosum of the rats with DED exhibited severe fibrosis and decreased smooth muscle content. Deposition of extracellular matrix proteins was increased in the diabetic rats, while expression of endothelial nitric oxide synthase/cyclic guanosine monophosphate/nitric oxide pathway-related proteins was reduced. Taurine supplementation ameliorated erectile response as well as histologic and molecular alterations. Conclusion: Taurine supplementation improves erectile function in rats with DED probably by potential antifibrotic activity. This finding provides evidence for a potential new therapy for DED. Copyright (C) 2016, International Society for Sexual Medicine. Published by Elsevier Inc. All rights reserved.