Different researches have evaluated the differences of gait in normal and PD cases.2,3 These studies generally focus on direct path walking. One problem is that straight walking in 3 to 5 minutes needs a proper place with nearly 100 m length, which is difficult to find in general clinics. On the other hand, in a direct path, the subject diminishes his/her gait disturbances because little control is needed in direct simple path to compensate the gait disturbances. Therefore, some components of the walking defects may be covered by more attention on the walking function. We think the circular path would be more proper for these patients; because less space is needed to do the test and the person cannot control his/her gait defects easily by concentration. On the other hand, we know that in primary stages of the disease it is more possible to have defects only in one side of the body.4 Therefore, we suppose that using an 8-shaped path for testing the gait would be useful for early diagnosis. In such path, centrifugal force is stronger to the right side in one of the circles of 8-shpaed path and to the left side in the other circle. Therefore, it seems that the patients, especially those in primary stages, may have more difficulty in one of the circles in respect to the other one.