This study aims to develop a quantitative measure of bradykinesia which can be conveniently used during clinical finger taps test in patients with Parkinson's disease. A miniature, light-weight gyrosensor free from gravitational artifact was used for measurement of finger taps in order to impose minimal constraint on patients. Forty Parkinson's disease patients and 14 age-matched control subjects participated in the experiments. Subjects' finger taps in both right and left hands were scored by two independent neurologists according to the unified Parkinson's disease rating scale and were also measured by a gyrosensor. Four performance indices were derived from the gyrosensor signal of the index finger. All indices showed significant differences between control and patients (P < 0.001) and also significant correlations with the clinical finger taps score (r = -0.73 to -0.80, P < 0.001). ANOVA showed significant differences in all indices among different finger taps scores (P < 0.001), and post hoc tests showed significant differences in indices between most pairs of non-neighboring and part of neighboring pairs of finger taps scores (P < 0.01). The results suggest that indices from a gyrosensor can be used as quantitative measures of bradykinesia during the finger taps test.