Asthma is the most common cause of recurrent wheezing, cough and dyspnea in childhood. Delay in diagnosis and lack of appropriate treatment can cause sustained changes which decrease respiratory capacity of children in future. Therefore, identifying the symptoms relating to asthma is the key for timely diagnosis and treatment of this disease. This study was done to investigate asthma incidence in khomein and compare it to other cities of Iran susceptible to asthma, including Tehran. The present study was a descriptive cross-sectional one based on standard questionnaire of International Study of Asthma and Allergies in Childhood (ISAAC). For conducting this study, 1621 students of first grade in some primary schools and junior high schools of khomein were selected through nonrandom sampling and census and were evaluated during 2015-2016. Both groups were studied and evaluated in terms of being affected by asthma and its severity (current and previous wheezing ,night-time cough, talking limitation due to coughing or wheezing, exercise-induced wheezing, nocturnal awaking due to cough). Results were analyzed through the chi-square test. The asthma diagnosed in Khomein students by the physician during the study was 3.5% while 73.2% of the children under study had at least one asthma symptom. One eighth of the students under study had severe asthma. Comparing with polluted Tehran and northern cities of Iran, Asthma symptoms incidence was higher in khomein where the humidity and industrial pollution is less than in those cities and the asthma cases diagnosed by physicians were much fewer than expected asthma incidence.