Gait disorders and falls are frequent in patients with parkinsonian syndromes. In patients with Parkinson's disease (PD), these signs occurred later during the course of the disease in comparison to patients with other degenerative parkinsonian disorders. The pathophysiology of these symptoms are still not fully understood. Gait initiation challenges the balance control system as the body moves from an upright stable static posture to a continuously unstable gait. The aim of this study is to analyse the gait initiation process in patients with parkinsonian disorders.