We studied the three most commonly used rating scales in Parkinson’s Disease (Hoehn and Yahr Clinical Staging, Webster Rating Scale, Columbia University Rating Scale) in order to examine the agreement between observers. Six neurologists, experts at using such scales, evaluated 48 patients suffering from the idiopathic form of Parkinson’s Disease. Reliability using the K index was moderate, although a slight superiority was found with the Columbia University Rating Scale. Analysis of the various items used has suggested that scales of disability could be a valid alternative to those examined.