Background: Mechanical Horse Riding Simulator (MHRS) is one of the complementary therapy used in the rehabilitation of children with cerebral palsy which produces rhythmical and repetitive movements. It is working under the principles of hippotherapy and considered an alternative method for hippotherapy. Purpose: This study aimed to nd out the effectiveness of a mechanical horse riding simulator on hip abduction range of motion in children with spastic diplegia and evaluate the magnitude of improvement at different periods (2 weeks, 4 weeks, and 6 weeks). This study included 30 childre Methods: n with spastic diplegia and was divided into two groups, the experimental and the control group. The experimental group received 15 minutes of complementary therapy with MHRS, 3 days/ week for 6 weeks along with regular physiotherapy, while the control group received 15 minutes of conventional trunk control exercise along with the regular physiotherapy session. Hip abduction passive range of motion (PROM) was measured with the Goniometer. Pre and postintervention scores were recorded and analyzed with appropriate statistical tools. The baseline characteristics were similar in both Results: groups before the intervention with the p-value (p>0.01). The observed mean value of hip abduction PROM has been improved in both groups over 6 weeks and the experimental group shows signicantly better improvement (p<0.01) than the control group in all the weeks. Conclusion: The study results conrmed that gradual improvement of hip abduction passive range of motion (both sides) was observed in both groups. Children exposed to MHRS show better improvement than the children in the control group. It was concluded that the MHRS is an effective complementary therapy improving hip abduction passive range of motion (both sides) in children with spastic diplegia and the provision of MHRS in longer duration provides more benets than the shorter duration.