Introduction. Stroke is the most common cause of neurological dysfunction, associated with high mortality and morbidity. Early stroke rehabilitation is essential for optional functional recovery, particularly motor control of the trunk muscles and balance. The study investigated the effects of Swiss-ball-based and plinth-based trunk exercises for improving trunk control and functional balance in subjects with sub-acute stroke. Methods. overall, 20 sub-acute stroke patients aged 40-60 years were recruited and divided into the experimental group (Swiss ball exercise) and the control group (plinth exercise). Upper and lower trunk exercises were performed by the patients sitting on a Swiss ball or a plinth. The 45-minute sessions were applied for 5 days a week for a total of 4 weeks. Trunk impairment Scale, Modified Functional Reach Test, and Functional Balance Scale evaluations were performed at baseline and at the end of the 4 weeks. Results. The differences between the baseline characteristics of participants in both groups were not significant. After the intervention, there were significant (p > 0.01) changes in the Trunk impairment Scale total, static, dynamic, and coordination scores, mental status, Modified Functional Reach Test results, and functional balance scores, with high effect sizes in the Swiss ball exercise group. Conclusions. in patients with sub-acute stroke, trunk exercises performed on a Swiss ball were found to be more effective than those performed on a plinth to improve trunk control, forward and lateral reach, and functional balance.