To investigate the effects of lateral sitting training on a tilting platform in persons with stroke. An assessor-blinded, randomized, controlled trial was carried out involving inpatients at a stroke rehabilitation center. Patients were allocated to either an experimental group or a control group. The experimental group sat without leg support on a platform tilted 10° to the paretic side in the frontal plane, while the controls sat on a horizontal platform. Both groups were asked to move their trunk laterally from the paretic side to the nonparetic side. Trunk function was assessed using the Trunk Control Test, and the ability to move the trunk laterally was evaluated kinematically. Measurements were performed at baseline and after training. Two-way repeated measures analysis of variance was used to test the significance between and within treatments for each dependent variable. None of the demographic data differed between the groups. After training, a significant improvement was noted in the experimental group compared to the controls in the TCT and the ability for lateral trunk transference.