Air pollution damages children’s health in many different ways, through both chronic and acute effects. The aims of our research are to reveal the indoor air quality levels in schools. Subject and indoor air measurements were performed in 34 primary schools located in the Central Anatolia region. PM10, PM2.5, CO2, CO, CH2O, relative humidity, temperature, and total bacteria and fungus levels were measured. In the urban region, mean PM1 was higher than the other regions(p=0.029). PM10 and PM2.5 were higher in schools in rural areas. According to CO2 measurements, only one school was identified to be below the upper limit recommended by the WHO. Total microorganism concentration was exceeded in 44.1% of classrooms. Indoor PM1, PM2.5, PM10, CO2, total bacteria and fungus levels were high and above recommended limits. Human activities, movements of students could be considered the most important indoor factors for particle matter increase. Indoor parameters could be lowered by organizing the school environment.