It has been suggested that malocclusions may influence whole body posture, including leg length, but the current scientific evidence to support this statement is poor. The aim of the present study was to investigate a possible association between leg length inequality (LLI) and unilateral posterior crossbite. A survey was carried out in young adolescents recruited from three schools. The sample included 1,159 subjects (633 males and 526 females) with a mean age of 12.3 years (range 10.1-16.1 years), who underwent an orthodontic and orthopaedic examination performed independently by orthodontists and orthopaedists. The data were analysed by means of logistic regression analysis. One hundred and twenty subjects (10.3 per cent) were diagnosed as having LLI. A unilateral posterior crossbite was found in 142 of the 1,159 subjects (12.2 per cent). Logistic multiple regression analysis, controlling for potential confounding variables, failed to reveal a significant association between LLI and unilateral posterior crossbite (odds ratio = 1.0, confidence limits = 0.6-1.9). A unilateral posterior crossbite does not appear to be associated with LLI, at least in young adolescents.