Background and Purpose: Cognitive impairment has been linked to poor motor learning and rehabilitation outcomes in older adult and stroke populations, but this remains unexplored in individuals with Parkinson disease (PD). The purpose of this secondary data analysis from a recent clinical trial (NCT02600858) was to determine if global cognition was related to nine-day skill retention after upper-extremity motor training in individuals with PD. Methods: Twenty-three participants with idiopathic PD completed three consecutive days of training on an upper-extremity task. For the purposes of the original clinical trial, participants trained either on or off their dopamine replacement medication. Baseline, training, and shorter-term (48-hour) retention data have been previously published. Global cognition was evaluated using the Montreal Cognitive Assessment (MoCA). Participant age, baseline performance, MoCA score, and group (medication on/off) were included in a multivariate linear regression model to predict longer-term (nine day) follow-up performance. Baseline and follow-up performance were assessed for all participants while on their medication. Results: MoCA score was positively related to follow-up performance, such that individuals with better cognition performed better than those with poorer cognition. Participant age, baseline performance, and medication status were unrelated to follow-up performance. Discussion and Conclusions: Results of this secondary analysis align with previous work that suggest cognitive impairment may interfere with motor learning in PD, and that assessing cognition could provide prognostic information about an individuals responsiveness to motor rehabilitation for a number of clinical populations.