Substantia nigra (SN) was assessed by transcranial sonography (TCS) in 47 Parkinson's disease (PD) patients and in 39 healthy volunteers. A semiquantitative echogenicity scale was created with arbitrary values ranging from 1 to 5, zones with grade >or=3 and larger than 0.19 cm(2) were recorded as hyperechogenic SN. TCS examination of SN as a diagnostic test for PD in our study showed 87.2% sensitivity and 94.9% specificity.