Objective: To determine the prevalence of symptoms of asthma, rhinitis, and atopic eczema in adolescents (AD; 13-14 years) living in seven Brazilian cities, by applying the standardized written questionnaire (WQ) of the International Study of Asthma and Allergies in Childhood (ISAAC), and to evaluate the time trend nine years after the last assessment of ISAAC phase 3 (ISP3). Methods: The ISAAC-WQ was answered by 20,099 AD from the Northern, Northeastern, Southeastern, and Southern Brazilian regions. Values obtained were compared to those observed in ISP3 using nonparametric (chi-squared or Fisher) tests, and the ratio of annual increment/decrement was established for each of the centers, according to the symptom assessed. DOI se refere ao artigo: http://dx.doi.org/10.1016/j.jped.2014.05.002 ଝ Como citar este artigo: Solé D, Rosário Filho NA, Sarinho ES, Camelo-Nunes IC, Barreto BA, Medeiros ML, et al. Prevalence of asthma and allergic diseases in adolescents: nine-year follow-up study (2003-2012). J Pediatr (Rio J). 2015;91:30---5.