The purpose of this study was to investigate the effect of aquatic lower limb muscle strengthening program on gait and lower limb function in hemiplegia stroke patient. Subjects were 20 hemiplegia stroke patients and they participated in the 12 weeks aquatic lower limb muscle strengthening program from June 2011 to August 2011. The exercise intensity was 12-16 (50-85% VO max) RPE. Gait analysis, lower limb function mobility, balance ability, lower limb muscle were measured before and after the exercise. Collected data were analyzed by paired t-test and independent t-test with using SPSS window 18.0 version. After aquatic lower limb muscle strengthening program, gait distance was significantly increased and gait course angle was significantly decreased. Lower limb function mobility, balance ability, lower limb muscle were also significantly increased after the program. Interestingly, after aquatic lower limb muscle strengthening program, left hemiplegia stroke patients presented significant increase in lower limb muscle than right hemiplegia stroke patients. In conclusion, aquatic lower limb muscle strengthening program improved gait distance, gait time, lower limb function in hemiplegia stroke patients. Therefore, aquatic lower limb muscle strengthening program is considered as proper rehabilitation exercise program for stroke patients.