Purpose The Purpose of this study was to investigate the effects of STS exercise using asymmetric initial foot position on paretic leg muscle activity and multiple task performance in chronic stroke patients. Methods Subjects were randomly assigned to the experimental group (n = 15) and the control group (n = 15). STS exercise was performed for 4 weeks, 3 times a week, 30 minutes at the asymmetric foot position which the paretic foot was located behind the nonparetic foot in the experimental group and at the symmetric foot position in the control group. Results There was a significant improvement pre and post exercise(p=.000) in the main effect on paretic leg muscle activity, but there was no significant difference between groups(p=.773). There were significant differences in TA(p=.040), BF(p=.020), and Sol(p=.034) except VM(p=.063) as interaction effects. There was a significant improvement in pre and post exercise(p=.000) and between groups(p=.043) in the main effect on multitask performance. There were also significant differences in interaction effects (p=.000). Conclusion In rehabilitation programs to improve paretic leg muscle activity and STS performance in chronic stroke patients, the initial foot position should be shifted from the asymmetric initial foot position to the symmetric initial foot position.