Background: This study investigated health-related fitness in adolescents with intellectual disabilities and analysed the various performances in physical fitness tests according to degrees of obesity. Materials and Methods: Eighty-seven French intellectual disabilities adolescents (14.24 [plus or minus] 1.48 years) performed the EUROFIT physical fitness test battery. Height, weight and waist circumference were assessed, and BMI and waist-to-height ratio were calculated. "Bio-impedancemetry" evaluated body fat (BF) percentage. Results: Ninety-four per cent of the adolescents completed the aerobic running test, 52% of which had low VO[subscript 2max]. Thirty-seven per cent were obese (%BF), and 32% had excess visceral adipose tissue. Adolescents with the lowest cardiorespiratory fitness had the highest BF percentages (P less than 0.001). Conclusions: Intellectual disabilities adolescents showed low physical fitness and high prevalence of obesity. Both could further worsen social participation and health status.