Botulinum toxin A (BoNT-A) injections are widely used to treat spasticity after stroke. Although this treatment is effective on muscle tone improvement, its effect on gait and ability of daily living on early stage of stroke adults remains uncertain.The purpose of this study is to determine whether an early calf muscle injection of low dose BoNT-A in severely affected patients within 6 weeks after stroke could help to hold back disabling muscle spasticity and improve walking dysfunction.