Standing balance of hemiparetic patients is characterized by increased sway and an asymmetrical weight bearing distribution. The objectives of the study were to determine the feasibility of using a modified clinical sensory organization test with patients following a stroke and to evaluate the contribution of visual and somatosensory input to the standing balance of hemiparetic patients during the first two months following a stroke. Thirty patients with hemiparesis underwent functional and posturographic testing one and two months following their stroke. Testing was conducted in six stance conditions differing in somatosensory and visual input. Fifteen age-matched non-impaired subjects served as the control group. Sway Index (SI) representing the displacement of the subjects' center of pressure during stance, was generally affected by time (p = 0.003), visual input (p = 0.0001), and somatosensory input (p = 0.0061), with the effect of vision significantly greater in the patient group as compared with the control group (p = 0.0006). Despite significant functional gains in the Barthel Index and functional ambulation (p = 0.01), percentage of body weight on the involved extremity (%BW) by stance condition did not change over time. Posturographic testing is useful for determining the sensory organization abilities of stroke patients with moderate impairment and indicates that these patients are dependent on visual input for postural control. The decrease in %BW borne on the affected extremity does not change over time or with the varying of sensory input.