Abstractc : Introduction: Asthma is the most common chronic respiratory disease of childhood and adolescence. People of all ages around the world are affected by this condition which, if not controlled, can limit the quality of life and sometimes even be fatal. It is estimated that asthma affects approximately 300 million individuals worldwide, projecting an increase of 100 million asthmatics in 2025. In Brazil, if we consider an average prevalence of 10% of physician-diagnosed asthma, there are approximately 20 million asthmatics. Objective: To analyze time trends in the prevalence of asthma and asthma symptoms and rhinoconjunctivitis, between 2001 and 2012 in schoolchildren from Florianópolis, aged 12 and 14 years. Methods: Two cross-sectional studies were conducted using the same methodology and the same questionnaire (ISAAC study) in schoolchildren from Florianópolis (SC) aged 12 and 14 years. The first study, conducted in 2001, involved 3053 students and the second, conducted in 2012, involved 2563 students. The response rate was 75,5% in 2001 and 81% in 2012. Results: The prevalence of reported asthma was 10.9% in 2001 and 14.8% in 2012 (p <0,001), with an average annual growth of 2,8% in the period. The highest average variation in the period of asthma was observed among female students (4,1%). This was paralleled by a significant increase in reported physician-diagnosed asthma of 7,3% in 2001 and in 2012 of 11.1% (p < 0,001) with an annual variation of 4,5%. The largest increases in the reported physician-diagnosed asthma occurred in girls (5,9%) and in students of public school (4,5%). Also, there was a significant increase in reported rhinoconjunctivitis, an average variation in the period of 5,2%.In contrast, reports of severe symptoms of asthma remained unchanged, while there was a decrease in the annual change in the period in the reporting of current wheezing (-1.3%) and wheezing after exercising (-1,2%). On the other hand, in both study periods, the reported severe symptoms of asthma, current wheeze, wheezing after exercising, nocturnal dry cough, rhinoconjunctivitis and physician-diagnosed asthma was significantly higher among students who reported asthma ever than among those who denied it. Conclusion: The results of this study demonstrate that, between 2001 and 2012 there was a significant increase in the annual variation in the reporting period in the prevalence of asthma and its symptoms and of rhinoconjunctivitis by schoolchildren aged 12 and 14 years in Florianópolis. This trend is well above that found in other countries and in Brazil, suggesting that local factors may be involved and deserve to be investigated in future studies.