Pathological gambling (PG) is a rare but well-established behavioural disorders of Parkinson's disease (PD) patients treated with dopamine agonist. We investigate the chronological relationship between PD and diagnosis of PG within treatment-seeking gamblers. Sample and Methods: From 174 consecutively admitted pathological gamblers we identified 4 patients with PD. Standardized medical records include socio-demographic characteristics, past gaming behaviours and gambling-treatment modalities as well as the evolution of PD and the pro-dopaminergic medication history. Results: All four patients developed PG after the onset of PD treatment. Three patients described a period of chronic exposure to gaming facilities years before and after onset of pro-dopaminergic treatment, with occasional or regular gambling, but without a compulsive component. In one patient, PG appeared suddenly without any previous gaming behaviour after the onset of medication. Despite a high treatment motivation, gambling specific cognitive therapy was unsuccessful.(c) Implication for the Field The relationship between PD and PG appears to be complex: Confounders such as psychosocial factors or increase in accessibility of gambling opportunities may account for these findings. This case series confirm that pro-dopaminergic treatment can induce PG behaviour, but may be more likely in "at risk" groups. These patients pose specific treatment challenges.