We analyzed the results of transcranial sonography (TCS) on 110 Parkinson's disease (PD) patients, 30 essential tremor (ET) patients and 110 controls in a Chinese population and compared our findings to the previous literatures. The echo signal intensity of midbrain substantia nigra (SN) was measured and divided into grade I-V. If the high echo signal intensity (grade III, IV or V) was detected in either side of SN, it was measured as well as the whole area of midbrain and the ratio of both sides of SN hyperechogenicity to the whole area of midbrain (S/M) were calculated. In addition, the width of the third ventricle in the level of thalamus was also determined. There were more individuals with the grade of SN a parts per thousand yen III in PD group (100/110, 85.45%) than these in ET group (4/30, 13.33%, x (2) = 58.38, P < 0.001) and control group (11/110, 10%, x (2) = 125.51, P < 0.001). The median and quartile range of SN hyperechogenicity area and S/M in PD patients were greater than those in ET patients and controls. Both the area of SN hyperechogenicity a parts per thousand yen0.2 cm(2) and the S/M a parts per thousand yen 0.07 were useful indexes to distinguish PD and ET in Chinese population. In conclusion, TCS is an effective and useful tool to detect PD and to distinguish PD from ET in Chinese patients.