Upright and upside-down photographs of faces, schematic drawings of faces, and photographs of houses were presented to patients with Parkinson's disease (PD), patients with right hemisphere stroke (RH), and age-matched normal control subjects (NC) in a forced- choice recognition paradigm. These slides were presented in four orientation conditions: upright at original presentation and at test, upside-down at both, upright initially and upside- down at test, and vice versa. NC subjects recognized faces most accurately when presented in the same orientation both times. This suggests that the information is resistant to mental rotation. Patients with PD recognized faces most accurately when they were presented upright both times, suggesting difficulty with any unusual orientation, consistent with an inability to shift mental set. RH patients, unlike the other groups, did not recognize faces presented upright both times more accurately than those in any other condirion. This supports previous studies suggesting a right hemisphere specialization for recognition of upright faces.