Objective: To evaluate the effects of sit-to-stand (STS) imagery group training (IGT) on STS movement and balance performance for chronic hemiparetic stroke. Design: Randomized controlled trial. Methods: A total of 30 people with chronic hemiparetic stroke (15 for STS-IGT group and 15 for control) were recruited in this study. The STS-IGT group participated in a videotape-based STS-IGT for 30 minutes a day, five days a week for six weeks, while the control group watched a documentary on television for the same period. The STS-IGT focused on a five-stage protocol. Specifically, external imagery was used during the four phases of the STS movement from the seat of the chair to standing up. All of the participants also participated in a regular rehabilitation program. STS movement and balance performance were assessed using three clinical measures. Results: After training, time to perform the 5-repetition STS test significantly increased in the STS-IGT group (change value, 4.0±2.0 sec) compared with the control group (change value, 0.9±0.7 sec) (p<0.05). There was a greater improvement in Berg balance scale scores in the STS-IGT group (change value, 0.2±4.1 points) compared with the control group (change value, 0.3±0.9 points) (p<0.05). There was a greater improvement in Timed Up and Go scores in the STS-IGT group (change value, 2.6±1.5 sec) compared with the control group (change value, 0.9±1.0 sec) (p<0.05). Conclusions: STS-IGT can be considered as a useful option for restoration of STS movement and balance performance for individuals with chronic hemiparetic stroke who are unable to fully participate in physical activities.