Despite being common, the pathophysiological mechanisms underlying the phenomenon of freezing in patients with Parkinson's disease (PD) remain poorly understood. Recent work has shown that freezing behaviour can be provoked through the use of a computer-based virtual reality task, allowing for the exploration of freezing with functional MRI (fMRI). This article describes a single patient with PD who performed a virtual-reality walking task, both "On" and "Off" dopaminergic medication, while fMRI data were obtained. The results showed distinct BOLD patterns during "walking", "dual-task walking" and during episodes of freezing. The results of this single study highlight the potential utility of this approach in elucidating the underlying neural correlate of freezing behaviour in PD.