The purpose of this study was: (a) to analyze the nutritional status and aerobic fitness in Chilean adolescents; and (b) to verify the association between the two variables in a sample of Chilean adolescents. The study was a descriptive crosssectional analysis of 155 adolescents (72 males and 83 females) from the province of Talca (Chile). The age range was 14 to 16 years. Weight, height, waist circumference, and two skinfolds (tricipital and subscapular) were evaluated. Body mass index (BMI) was calculated and the two skinfolds were summed (Σ(Tr+Sb). Aerobic fitness was measured by cardiopulmonary exercise test (TECP) in the laboratory. The males’ nutritional status consisted of 44.5% normal weight, 13.8% overweight, and 41.7% obese. In the females, 45.8% were normal weight, 26.5% were overweight and 27.7% were obese. In aerobic fitness, 94.4% of the males were unhealthy and 5.6% were healthy, while 92.37% of the females were unhealthy and 7.3% were healthy. In general, in both sexes there was a significant association between both variables (X2 = 13.17, P<0.05). High prevalence of overweight, obesity, and unhealthy aerobic fitness was verified, and an association between nutritional status categories and aerobic fitness levels was observed in adolescents of both sexes. The results suggest promoting in adolescents not only a healthy weight, but also a physically active lifestyle to counteract the deterioration of their aerobic performance and well-being.