The study was done to evaluate the efficacy, safety, and tolerability of orally administered sildenafil taken as needed about one hour before sexual activity after a 10-week period in male outpatients with erectile dysfunction and severe renal failure who were on hemodialysis.

Inclusion Criteria:

• Included patients had been in a stable relationship with a female partner for at least 6 months
• A diagnosis of renal failure, with creatinine clearance ≤10 ml/min; been under hemodialysis for at least 6 months prior to the screening period, and a clinical diagnosis of erectile dysfunction (ED) as confirmed by International Index of Erectile Function (IIEF-5) score of <21 and defined as an "incapacity to obtain and/or maintain an erection sufficient for a satisfactory sexual performance".

Exclusion Criteria:

• Patients in regular use of nitrates or nitric oxide donor drugs, or have received a prescription to use these substances in any formulation
• Patients with genital anatomic malformation that may significantly impair erection (e.g., serious penile fibrosis)
• Patients with other sexual disorders (e.g., hypoactive sexual desire) considered as a primary diagnosis, with a coexisting ED diagnosis, including patients receiving anti-androgenic therapy whose libido has not been preserved; patients receiving hormonal replacement therapy for at least 6 months, or whose dose has not been stabilized within the last 6 months before the study screening period
• Patients with diabetes mellitus presenting poor control of their diabetes and/or proliferate diabetes retinopathy.