Fourteen male patients suffering from Parkinson's disease, each of whom had been treated with L-DOPA, and in whom additional treatment with oral dopamine agonist (DA) was needed, were followed for a period of one year. Pergolide mesylate (Permax) was given to each patient, and titrated to a total daily dose of 3 mg. All of the patients were taking L-DOPA. The assessments performed before the start of pergolide treatment consisted of neurological examination, unified Parkinson's disease rating scale (UPDRS) III and IV subscales scoring, mini mental state examination (MMSE) scoring, the neuropsychological examination including Zung scale scoring, biochemical and hematological examinations including prolactine serum levels; and a sexological examination during which the patients filled-in the international index of erectile function (IIEF) questionnaire. These examinations were repeated during the control assessments at months 1, 3, 6 and 12. ANOVA, non-parametric Friedmann's ANOVA and Tukey post hoc tests were used for the statistical analysis. There were statistically significant differences between the values of UPDRS III motor subscale and all subscales of IIEF when months 0 and 1 were compared with the results obtained at months 3, 6 and 12. Pergolide mesylate, when added to L-DOPA, significantly improved all sexual functions in younger male Parkinsonian patients who were still interested in sexual activities. The treatment with pergolide in these cases might be more beneficial than with short-acting PDE-5 inhibitor sildenafile. Nevertheless, the relationship between pergolide treatment and incidence of restrictive valvular heart disease must be considered.