In 21 male patients with multiple sclerosis according to the International Index of Erectile Function (IIEF-5) in 10 (47.6%) serious erectile dysfunction was detected. The mean age of the patients was 41.7 years (28-52 years), mean duration of multiple sclerosis 8.2 years, mean score of Kurtzke's disability stale 3.5 (1.5-5.5). In these 10 patients in a clinical study the effectiveness and lafety of sidenafil (VIAGR.A) was evaluated as the drng of hrst choice in the treatment of erectile dysfunction in multiple sclerosis. According to IIEF-5 in 7 patients (70%) a significant improvement of erection was recorded, ability of penetration, ability to maintain erection to the end of intercourse, very satisfactory experience of intercourse and a significant sensation of improved quality of life. The effective therapeutic dole of sildenafil was 50 mg, in one patient 100 mg. During treatment no serious undesirable symptoms esere observed, only in one instance slight headache and once reddening of the face. Sildenafil is beyond doubt a very effective drng of first choice in the treatment of erectile dysfunction in patients with multiple sclerosis.

        Key words: multiple sclerosis, International index of erectile function (IIEF-5), erectile dysfunction, sildenafil (Viagra), mechanistu of action, significantly increased therapeutic effect, contraindications of sildenafil