Modern concepts of gait rehabilitation after stroke favor a task-specific repetitive approach. The aim of the study is to test the efficacy of a body weight support treadmill training technique enabling nonambulatory patients to have the repetitive practice of a gait-like movement compared to a conventional rehabilitation program in the acute phase. Hemiparetic stroke patients will be randomly included in a 4 week rehabilitation program associating physiotherapy and gait trainer therapy or physiotherapy alone.