Objective: To investigate the longitudinal dose-effect relationship between dopamine replacement therapy and impulse control disorders (ICDs) in Parkinson’s disease (PD). Methods: We used data from a multicentre longitudinal cohort of consecutive PD patients with ≤5y disease duration at baseline followed annually up to 5y. ICDs were evaluated during face-to-face semi-structured interviews with movement disorder specialists. Generalized estimating equations Poisson models with robust variance were used to study the association between several time-dependent definitions of dopamine agonist (DA) use, taking dose and duration of treatment into account, and ICDs at each visit; other antiparkinsonian drugs were also examined. Results: Among 411 patients (40.6% women; mean age=62.3y, average follow-up=3.3y, SD=1.7y), 356 (86.6%) took DA at least once since disease onset. In 306 patients without ICDs at baseline, the 5y cumulative incidence of ICDs was 46.1% (95% CI=37.4-55.7; DA ever-users=51.5% [41.8-62.1]; DA never-users=12.4% [4.8-30.0]). ICDs prevalence increased from 19.7% at baseline to 32.8% after 5y. ICDs were associated with ever DA use (prevalence ratio, PR=4.23 [1.78, 10.09]). Lifetime average daily dose and duration of treatment were independently associated with ICDs, with significant dose-effect relations. Similar analyses for levodopa were not in favour of a strong association. ICDs progressively resolved after DA discontinuation. Conclusions: In this longitudinal study of PD patients characterized by a high prevalence of DA treatment, the 5y cumulative incidence of ICDs was ~46%. ICDs were strongly associated with DA use, with a dose-effect relationship; both increasing duration and dose were associated with ICDs. ICDs progressively resolved after DA discontinuation.