Objectives. Sensorimotor deficits such as impaired joint proprioception and muscle weakness have been found in association with hypermobility syndrome (HMS) in adults. HMS is more common in children than adults, yet such deficits have not been adequately investigated in paediatric populations. It is therefore uncertain as to what sensorimotor deficits are present in children with HMS. This study investigated knee joint proprioception and muscle torque in healthy children and those with HMS. Methods. Thirty-seven healthy children (mean age S.D.¼11.52.6 yrs) and 29 children with HMS (mean age S.D.¼11.91.8 yrs) participated in this study. Knee joint kinaesthesia (JK) and joint position sense (JPS) were measured, with the absolute angular error (AAE) calculated as the absolute difference between the target and perceived angles. Knee extensor and flexor muscle torque was assessed and normalized to body mass. Mann–Whitney U-tests were performed to compare JK, JPS and muscle torque between the two groups. Results. Children with HMS had significantly poorer JK and JPS compared with the controls (both P