This randomised, double-blind study assessed the long-term efficacy and tolerability of vardenafil 10 and 20 mg in men with erectile dysfunction (ED). A total of 566 men who completed an initial 12-month treatment period entered a 12-month extension. In these men, both doses of vardenafil produced improvement in scores for the ‘erectile function’ Domain of the International Index of Erectile Function, evident from week 4 and maintained through 2 years. Sexual Encounter Profile diary responses indicated that following treatment, penetration was achieved on 92–94% of attempts and erections that lasted long enough for successful intercourse were achieved on 87–89% of attempts. In response to the General Assessment Question, 90–92% of patients reported improved erections with vardenafil. Most treatment-emergent events were mild and transient with no cardiovascular safety concerns. These results support the long-term efficacy, reliability and tolerability of vardenafil 10 and 20 mg in men with ED.