Purpose This study aimed to investigate the effects of trunk stabilizationbased functional reaching training on anterior deltoid (AD), erector spinae muscle (ES) activity and upper limb function in patients with chronic stroke. Methods This study used a randomized controlled pretestposttest design. Nine patients with chronic stroke were included in the final analysis and were assigned to either the experimental group (EG) (n=4) or the control group (CG) (n=5). EG received trunk stabilizationbased functional reaching training, which focused on maintaining pelvic and trunk alignment while performing repeated reaching tasks with the affected upper limb. CG received conventional occupational therapy, including reaching and upper limb functional tasks. Both groups received intervention for 40 minutes per session, 5 times per week, for 4 weeks. Outcome measures included surface electromyography (sEMG) activity of the AD, ES, and the manual function test (MFT). Results The changes in AD and ES muscle activity were significantly greater in EG than in CG (p<.05). However, there was no significant difference between the two groups in the change in MFT scores (p>.05). Conclusion Trunk stabilizationbased functional reaching training improved AD and ES muscle activity in patients with chronic stroke. These findings suggest that this training may help facilitate AD and ES muscle activity during functional reaching in patients with chronic stroke.