Abstract Objectives The aim was to investigate whether argirein, which releases rhein and l-arginine after medication, could improve erectile dysfunction (ED) in diabetic rats through normalising the abnormalities of nitric oxide synthase (NOS), p66Shc and immunoglobulin heavy-chain binding protein (Bip), in the corpus cavernosum (CC). Methods SD rats were randomly divided into six groups. Except for the control group, rats were injected with streptozotocin (STZ) (60 mg/kg, i.p.) once. During weeks 5–8 following STZ injection, except for STZ-injected untreated rats, others were treated with aminoguanidine (AMG; 100 mg/kg/day, i.g.), or argirein at three doses (50, 100 and 200 mg/kg/day, i.g.). The vascular activity and biomarkers of the cavernosum were examined. Key findings Constrictive and dilative activity was abnormal in the CC, associated with decreased nitric oxide (NO) in serum in the diabetic (DM) group. Increased expression of p66Shc, Bip and inducible nitric oxide synthase (iNOS) and decreased endothelial nitric oxide synthase (eNOS) in the CC were significant in DM rats. Argirein and AMG improved these abnormities significantly. Conclusions We concluded that vascular activity of the cavernosal tissue was impaired due to upregulated p66Shc and Bip in the diabetic CC. Argirein alleviates the vascular dysfunction of the CC by suppressing these upregulated pro-inflammatory proteins caused by diabetic lesions.