Several studies have shown mixed results about the relationship between academic achievement and physical fitness (PF). Therefore, there is a need for more research investigating this association. PURPOSE: The purpose of this study was to determine the association between academic achievement, physical fitness and participation in organized sports and physical activities in 5th and 7th grade students attending urban public schools in Madeira Island. METHODS: The total sample included 345 5th grade and 388 7th grade boys and girls (10.4±0.8 and 12.5±0.9 years old, respectively), attending 2 public schools in Funchal, Madeira Island. Achievement of PF was assessed as the number of tests above the healthy fitness zone (HFZ) from the Fitnessgram test battery, and the aerobic capacity through the Pacer test. Percent body fat (%BF) was estimated using equations developed by Slaughter et al. (1988). Participation in organized sporting activities was assessed by questionnaire, asking about club and school sports participation during the last 3 years. All students attended compulsory physical education classes. Academic achievement was determined by averaging the final scores obtained by the students in all compulsory class subjects, at the end of 2009/10. RESULTS: Regarding participation in organized activities, there were significant differences between genders, with boys reporting higher levels of sport participation (p<.001), and for a longer period (p<.001) than girls. Estimates of %BF were not associated with levels of sport participation (p>.05), but they were negatively associated with aerobic performance (r=-.45; p<.001). Students who reported participating in organized sports for the previous 2 to 3 years, had on average better grades (p<.001), than those who had not played any sports during the same period. A positive association (r=.23; p<.001) was noted between academic scores and the number of tests in the HFZ, as well as the number of years playing sports. CONCLUSION: This study showed that students who participated in organized sports and activities were more likely to have higher academic scores. There was a stronger association for those who had been playing more sports and for longer periods, especially in girls. Sponsored by the Research Center of Sport, Health and Human Development (CIDESD)