BACKGROUND: There is insufficient clarity regarding whether or not drugs used in asthma cause behavioral problems in children. METHODS: A total of 155 individuals, categorized into an asthma group (n = 95) and a control group (n = 60), were enrolled in the current prospective controlled study. The asthma group consisted of patients receiving treatment (inhaled corticosteroids [ICS] or montelukast) for at least 1 month. Check Behavior Checklist (CBCL) for ages 1.5-5 scores for the asthma and controls were compared. The asthma group was divided into two subgroups based on prophylactic therapy received, ICS and montelukast, and these groups' CBCL scores were also compared. RESULTS: The asthma group consisted of 95 children (ICS subgroup 45, montelukast subgroup 50) and the healthy control group of 60 cases. The mean total CBCL score was higher in the asthma group than in the control group (42 vs 32, respectively, P = 0.001). Internalization and externalization scores were also higher in the asthma group compared to the control group (P = 0.004 and P = 0.005, respectively). No significant difference was determined in terms of CBCL scores between the ICS and montelukast groups (P = 0.3). Montelukast was discontinued in one asthmatic child due to hallucination. CONCLUSION: This study determined a higher rate of behavioral problems in preschool children with asthma compared to healthy children. In contrast to other studies in the literature, we determined no difference in terms of total CBCL, and internalization and externalization scores of children with asthma who received ICS and montelukast. Nevertheless, it should be kept in mind that montelukast may cause serious neuropsychiatric events such as hallucination.