Objective: This study analyzes and describes trends in prevalence of asthma and rhinitis in children 6-7 years old living in Santo Ângelo, Brazil, by comparing data from 2007, 2012, and 2017. Methods: The ISAAC (International Study of Asthma and Allergies in Childhood) standardized written questionnaire was used in a three cross-sectional survey. The questionnaire was applied between March and May of 2007, 2012 and 2017. Results: A total of 701 children participated in the survey: 225 children in 2007, 229 in 2012, and 247 in 2017. There were no differences in the prevalence of current wheeze in the years of this study. On the other hand, a higher percentage of children were diagnosed with asthma in 2012 (26.2%) than in 2007 (10.2%) and 2017 (10.1%) (p < 0.05); however, the severity of asthma was lower in 2012 when compared to other years. Regarding cases of probable asthma - which included patients with suspected asthma or wheezing and nocturnal cough without a diagnosis of asthma - these corresponded to 15.7, 17.0, and 25.1% of the cases in 2007, 2012 and 2017, respectively. For other allergic diseases, we found no statistical difference in the frequency of symptoms of current rhinitis (55.5%, 54.6%, 51.8% in 2007, 2012, and 2017, respectively), allergic rhinitis (45.3%, 45.0%, 36.4% in 2007, 2012, and 2017, respectively), or pollinosis (17.8%, 12.7%, 14.2% in 2007, 2012, and 2017, respectively). Conclusions: The prevalence of probable asthma increased from 2007 to 2017. The prevalence of symptoms and diagnosis of allergic rhinitis and pollinosis was relatively high and these allergies must be considered in the pediatric population of the region.