To compare the ability of T2*-weighted gradient echo (GE) and T2-weighted fast spin echo images to distinguish between patients with idiopathic PD and multiple system atrophy (MSA), the authors studied 15 patients with probable MSA, 40 patients with PD, and 17 healthy control subjects. Hypointense putaminal signal changes were more often observed in MSA than in PD using T2* but not T2-weighted images, indicating that T2*-weighted GE sequences are of diagnostic value for patients with parkinsonism.