The main aim of this study was to investigate the relationship between dopaminergic markers and brain volumes for striatal and cortical structures, and cognitive performance in patients with Huntington's disease and control subjects. We used PET and MRI data as predictors of performance in tasks assessing executive function, visuospatial ability, episodic memory, verbal fluency, perceptual speed and reasoning. The dopamine neurotransmission parameters (D1 and D2 receptor density and dopamine transporter density) and the volumetric measurements for caudate and putamen accounted for substantial portions of the variance across the majority of cognitive tasks. In addition, frontal volume showed a strong relationship with all cognitive tasks. D1 binding and volume measurements for the temporal cortex and thalamic volume showed associations with a select number of cognitive tasks. The overall data pattern is consistent with the view that Huntington's disease may be characterized as a frontostriatal dementia, in which cognitive deficits may result from pathological changes at multiple sites in the frontostriatal circuitry.