Background : Following stroke, patients are often left with hemiparesis that reduces balance and gait capacity. Arecent, non-invasive technique, transcranial direct current stimulation, can be used to modify cortical excitabilitywhen used in an anodal configuration. It also increases the excitability of spinal neuronalcircuits involved in movementin healthy subjects. Many studies in patients with stroke have shown that this technique can improve motor, sensory andcognitive function. For example, anodal tDCS has been shown to improve motor performance of the lower limbs inpatients with stroke, such as voluntary quadriceps strength, toe-pinch force and reaction time. Nevertheless, studies ofmotor function have been limited to simple tasks. Surprisingly, the effects of tDCS on the locomotion and balance ofpatients with chronic stroke have never been evaluated. Inthis study, we hypothesise thatanodaltDCSwillimprovebalance and gait parameters in patients with chronic stroke-related hemiparesis through its effects at corticaland spinal level. Methods/design : This is a prospective, randomised, placebo-controlled, double-blinded, single-centre, cross-over studyover 36 months. Forty patients with chronic stroke will be included. Each patient will participate in three visits: aninclusion visit, and two visits during which they will all undergo either one 30-min session of transcranial directcurrent stimulation or one 30-min session of placebo stimulation in a randomised order. Evaluations will becarried out before, during and twice after stimulation. The primary outcome is the variability of the displacementofthecentreofmassduringgaitandastatic-balancetask. Secondary outcomes include clinical and functionalmeasures before and after stimulation. A three-dimensional gait analysis, and evaluation of static balance on aforceplatformwillbealsoconductedbefore, during and after stimulation. Discussion : These results should constitute a useful database to determine the aspects of complex motorfunction that are the most improved by transcranial direct current stimulation in patients with hemiparesis. Itis the first essential step towards validating this technique as a treatment, coupled with task-oriented training. Trial registration : ClinicalTrials.gov, ID: NCT02134158. First received on 18 December 2013; last updated on 14September 2016. Other study ID numbers: P120135 / AOM12126, 2013-A00952-43.