PURPOSE: Knee function is reduced in patients with Benign Joint Hypermobility Syndrome. The aim was to study knee function in children and adults with Generalised Joint Hypermobility (GJH) and Non-GJH (NGJH)). MATERIALS AND METHODS: In a matched comparative study, 39 children and 36 adults (mean age children 10.2years; adults 40.3years) were included, comprising 19 children and 18 adults with GJH (Beighton =5/9; Beighton =4/9), minimum one hypermobile knee, no knee pain (children), and 20 children and 18 adults with NGJH (Beighton