OBJECTIVES: Evaluate the use of probiotics as an additional therapy in the treatment of children and adolescents with asthma in Belo Horizonte, MG-Brazil. METHODS: A pilot longitudinal, experimental and nonrandomized study with 30 patients from six to 17 years old from Belo Horizonte. In the baseline appointment, all patients received beclomethasone, and one group also received a probiotic containing Lactobacillus reuteri (n=14). The patients were reassessed after at least 60 days with the Asthma Control Test, spirometry and self-report of the symptoms they experienced associated with asthma. RESULTS: A predominance of male patients (56.7%) and a mean age of 10.6 years were observed. The groups using probiotics did not differ in terms of sex, age or atopy. In the longitudinal evaluation, an increase in the Asthma Control Test scores and a reduction in the number of symptoms were observed in the probiotic group. There was an increase in the peak expiratory flow among those who used probiotics. CONCLUSIONS: This pilot study supports the hypothesis that the administration of probiotics as a supplementary therapy for the treatment of children and adolescents with asthma improves the clinical condition of the patients. Further studies are needed to confirm the efficacy of probiotics in asthma treatment.