Objective: The purpose of this study was to investigate the effects of aqua-noodles on the practice of underwater walking in patients with hemiplegia. Method: After an oral explanation and signing an IRB approved consent form 10 participants (66.8±10.75 yr, 165.3±8.79 cm, 73.6±46 kg) agreed to participate in this study. Each of the participants was required to walk with the aqua noodles and without the aqua-noodles in a swimming pool. Each participant was asked to walk a distance of 5 m a total of 10 times, 5 with and 5 without the aqua-noodles. The depth of the swimming pool was at 1.3 m, approximately chest height. The following variables were calculated for analysis; height of the knee (m), knee joint ROM (°), ankle joint ROM (°), knee joint maximum angular velocity (°/sec), and ankle joint maximum angular velocity (°/sec). Results: First, there was a significant increase in time (s) for the maximum knee height to reach as well as the maximum knee height (m) increased when the participant used the aqua-noodles. Second, there was a statistically significant decrease in stride length when the aqua-noodles were used. Conclusion: This study helps to verify that the effect of underwater walking exercise can provide a suitable walking exercise environment. The results of this study provide systematic scientific information about how walking in water can be used for the rehabilitation of patients and the elderly.