Impairment of trunk control is a common problem after stroke, and trunk impairment may affect many functions such as breathing, speech, limb movements and transfers. The present study was aimed to investigate the effect of trunk control on sitting balance and upper extremity functions in individuals with subacute stroke. A total of 30 patients with subacute stroke (14 female, 16 male) were included in this study. The mean age of the included patients was 59.80 ± 13.22 years, and the mean disease duration was 2.90 ± 1.38 months. Trunk Impairment Scale (TIS), Trunk Control Test (TCT), Function in Sitting Test (FIST), Fugl-Meyer Assessment Upper Extremity (FMA-UE), Brunnstrom Recovery Stages of Arm (BRS-A) and Brunnstrom Recovery Stages of Hand (BRS-H) were performed to the patients. The results of our study showed that there was a strong positive correlation was found between TIS and FIST (r = 0.765, p < 0.001). There was also a positive moderate correlation between TCT and FIST, FMA-UE, BRS-A and BRS-H (r = 0.67, r = 0.49, r = 0.49, r = 0.44; p < 0.05; respectively). There was a positive moderate correlation between TIS and FMA-UE, BRS-A and BRS-H (r = 0.67, r = 0.65 and r = 0.58; p < 0.005; respectively). In conclusion, trunk control has been shown to be a factor associated with sitting balance and upper extremity function in patients with subacute stroke.