Analysis of the spatio-temporal and kinematic parameters of locomotion recorded in 21 parkinsonian patients compared to 58 normal elderly subjects showed significant differences in all the recorded parameters. However the relationship between these parameters was preserved, as was the basic locomotor pattern. The variability of stride length, more marked in parkinsonian patients, increased as a function of the clinical stages of Hoehn and Yahr. This index could be useful in assessing the course of the disease in patients.