Childhood obesity has become most prominent public health concern in the United States. Obesity and lower physical fitness, may cause low self-esteem and depression, these two psychological disorders may affect academic performance. PURPOSE: of this study was to investigate whether levels of obesity and physical fitness have an influence on academic performance in Hispanic adolescents. METHODS: Body mass index (BMI), one mile run and curl-up scores from 1,720 Hispanic adolescents in grades 8-11 were collected. Students were classified into four groups for BMI score using CDC weight status cut point (underweight, health weight, overweight, and obese) and three groups for aerobic fitness (one mile run) and muscle strength (curl-up) using FITNESSGRAM standards (ES: exceed standard, MS: meet standard, and US: under standard). Reading and Mathematics scores in Texas Assessment of Knowledge and Skills (TAKS) test were obtained from a South Texas school district. RESULTS: Obese students scored lower than other groups in reading (36.2±.8 vs. 43.1±.6, Mean±SE, P<.01) and mathematics (34.5±.9 vs. 40.8±.8, P<.05) in 11th grade and scored lower in reading only in 10th grade (38.6±.8 vs. 43.8±.5, P<.05). However, there was no relation between the level of obesity and TAKS scores in 8 and 9th grades. In 8th grade, ES in one mile run scored higher than US in reading (42.7±.7 vs. 39.5±.5, P<.05) and mathematics (40.2±.9 vs. 32.5±.7, P<.01) and also ES in curl-up scored higher than US in both reading (41.4±.5 vs. 38.2±.9, P<.05) and mathematics (37±.7 vs. 31.8±1.0, P<.01). 9th grade ES in one mile run or curl-up scored higher than US in mathematics (32.9± 1.5 vs. 28.3±.8 and 31.2±.9 vs. 26.3±1.4 in one mile run and curl-up, P<.05). In 10th grade, only ES in aerobic fitness was associated with higher scores in mathematics (41.5±1.1 vs. 33.1±.9, P<.01). None of physical fitness measures correlated with TAKS scores for the 11th grades. CONCLUSIONS: Analysis of the data suggests that higher BMI and lower levels of aerobic and muscle fitness are associated with lower academic achievement in Hispanic adolescents. Results indicate that academic achievement is more affected by physical fitness, such as aerobic fitness and muscle strength, in early adolescence and it is more affected by level of obesity (body image) in late adolescence.