A quantitative analysis of the so-called finger-tapping test was performed on 111 normal subjects. Quantitative analysis was also performed on 17 patients with cerebellar diseases, 14 with parkinsonism, and 14 with hemiparesis. All analyses were performed in a simple fashion using an 8-bit microcomputer fed through an electrocardiographic apparatus. The results in normal subjects were as follows: (1) tapping frequency lowered with advancing age; (2) men tapped faster than women; and (3) tapping with the dominant finger was faster than tapping with the nondominant finger in normal subjects. Tapping frequency can distinguish patients with motor dysfunctions of cerebellar, basal ganglia, and cerebral origins from normal subjects. Only the time-sequential histograms of tapping intervals could distinguish the motor dysfunctions studied.