Resumo. ABSTRACT People with Down Syndrome (DS) present metabolic differences when compared to the general population, which ends up at a higher prevalence of overweight and lower rates of aerobic fitness. The aim of this study was analysing the association of aerobic fitness and body composition in individuals with DS. Thirty individuals with DS from the city of Londrina / Brazil with a mean age of 18.00±3.66 years were evaluated. The variables body mass index, body fat, and aerobic fitness (VO²peak) were investigated. Men were taller than women, presented a higher percentage of lean body mass and higher VO²peak, while women showed higher means for android, gynoid and total fat. Aerobic fitness was positively associated with bone mineral density and inversely associated with nutritional status, lean body mass and body fat.