The purpose of this study was to investigate the effects of active and passive postural perturbation on ankle dorsiflexor responses in stroke patients. The subjects consisted of 13 stroke patients. Using wireless electromyography, the patients’ ankle dorsiflexor muscle responses were measured under the following conditions: active dorsiflexion (AD), active perturbation (AP), and passive perturbation (PP). Tibialis anterior muscle activity increased most significantly during PP of the affected side (118.64±56.28). The most significant increase for the non-affected side was in AD (72.64±24.56). Tibialis anterior muscle activity was compared under each condition. The affected side showed significant differences between PP and AD and between PP and AP (p<.05). The non-affected side showed not significant differences between each condition. The ratios of tibialis anterior muscle activity under AP to that under AD were 1.00 on the affected side and .75 on the non-affected side and the difference was not significant (p>.05). The ratios of tibialis anterior muscle activity under PP to that under AD were 3.30 on the affected side and 1.14 on the non-affected side and the difference was significant (p<.05). Passive perturbation improved tibialis anterior muscle activity on the affected side, and training based on this approach may have the potential to improve the ankle dorsiflexion of people with stroke.