In a large longitudinal study of 411 patients with early Parkinson’s disease, 356 (86.6%) were treated with a dopamine agonist at least once since the onset of their illness. In 306 patients who were known to have no evidence of an impulse control disorder (ICD – e.g. compulsive gambling or impulsive sexual behaviour) at baseline, the 5-year cumulative incidence of these phenomena was 46.1% in total, 51.5% for those who had been “ever-users” of dopamine agonists, vs 12.4% for “never-users.” The prevalence of impulse control disorders increased from 19.7% at baseline to 32.8% after 5 years. ICDs were strongly associated with ever DA use (prevalence ratio 4.23, 95% CI 1.78–10.09). Similar analyses for laevodopa were not in favor of a strong association. ICDs progressively resolved after DA discontinuation. Ongoing monitoring for the emergence of these effects after the initiation of dopamine agonists such as cabergoline, pramipexole or rotigitine appears to be warranted.