To test the hypothesis that recovering stroke patients with initially good sitting balance or those who develop good sitting balance during rehabilitation have better Barthel Index-based functional assessment outcomes than recovering stroke patients with poor sitting balance, we prospectively studied 24 of 25 consecutive stroke patients admitted to a tertiary-care hospital rehabilitation unit. Sitting balance, a prerequisite for most functional activities, was scored using a four-point scale evaluating static and dynamic sitting balance on admission to the rehabilitation unit and weekly until discharge. Functional status was assessed using the Barthel Index 4 or 12 weeks after the stroke. We found a strong positive correlation between Barthel Index score and each weekly sitting balance score. Multiple evaluations over time identified those patients whose sitting balance improved during rehabilitation in our unit; after grouping the patients into those with normal, improved, and poor sitting balance, we found a significant difference in the Barthel Index scores among the three groups. The group of patients whose sitting balance improved had higher Barthel Index scores than the group whose sitting balance did not improve. Ongoing evaluation of sitting balance can be helpful in anticipating functional status at discharge in stroke patients undergoing comprehensive rehabilitation.