Aims: The aim was to study the indoor air quality (IAQ) levels inside the governmental elementary schools of Dammam City in Kingdom of Saudi Arabia (KSA) and study factors affecting these levels. Materials and Methods: Sixteen schools were selected for this study; 12 of them were representing governmental constructed buildings, while the other 4 schools were representing rental buildings. Levels of dust or total suspended particulates (TSP), carbon monoxide (CO), carbon dioxide (CO 2 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), and benzene; in addition to temperature degree and relative humidity percent were measured during this study at four selected locations inside each school and one location outside it. Results: The highest levels of all pollutants were found inside classrooms that were located directly on the moderate traffic streets compared with low or very low traffic activity ones. Levels of most air pollutants inside the governmental constructed buildings were higher than those inside the rental type of schools. Conclusion: The average levels of TSP, NO 2 and CO inside all selected schools were lower than the air quality guidelines (AQGs). In contrary, all mean levels of CO 2 and nearly 50% of SO 2 and benzene levels were higher than their AQGs. Increasing the efficiency of the mechanical and air condition systems inside classrooms is important for appropriate ventilation and improving IAQ level.