Effect of Swiss Ball Exercise on Trunk Ability and Postural Sway in Stroke Patients. KINESIOLOGY, 2016, 18(2): 71-80. [PURPOSE] The purpose of this study was to investigate the effects of Swiss ball exercise on trunk ability and postural sway in stroke patients. [METHODS] The subjects were comprised of 30 stroke patients (experimental group, n=15; control group, n=15). The exercise program consisted of performing Swiss ball exercise (30 min) and trunk stabilizing exercise (30 min) once daily for five days per week for six weeks. Changes in trunk ability were meas-ured using the trunk impairment scale (TIS), the postural assessment scale for stroke (PASS), and a trunk control test (TCT), and postural sway (X, Y, and Z axes) was measured by a 3-axis wireless accelerometer pre- and post- exercise program to ver-ify the effectiveness of the exercise. The Wilcoxon signed-rank test was used to compare each group before and after the inter-vention, and the Mann–Whitney U test was used to compare the groups after the intervention. The statistical significance was set to be α=.05. [RESULTS] Between each group, significant differences in all of the dependent variables before and after the experiment (p<.05) were observed. Between the two groups, the experimental group showed more significant improvements ac-cording to the TIS, PASS, and all axes of the postural sway, but showed no significant improvements according to the TCT. [CONCLUSION] Our results suggest that applying Swiss ball exercise provides beneficial effects on trunk ability and postural sway in stroke patients.