The classrooms for elementary, middle and high schools are mostly occupied during the daytimes. However, most of the domestic school classrooms depend upon electric lighting due to the lack of proper daylighting design. Our recent survey on school classrooms revealed that most of the classrooms were equipped with textile curtains or manually operated blinds to block strong sunlight on the area near the windows. However the shading devices significantly reduced entire illuminance levels across the classrooms. Previous studies in foreign countries demonstrated that daylighting in school had many beneficial effects on the students such as improvement of physical and mental healths, performance of study, and attendance ratios of students. In addition, daylighting also reduces electric energy for lighting. Our survey on architectural characteristics of domestic school classrooms showed that the ceiling cavities were not as much congested as those of commercial buildings. The ceiling cavities of the domestic school classrooms usually accommodated only lighting fixtures and ceiling-mounted air-conditioning units, because most of the school buildings were not equipped with centralized mechanical systems which use ceiling spaces for air ducts, water pipes, and electric conduits. This study aims to develop an anidolic daylighting system in which the ceiling cavity is used as light duct to transfer daylight into the deep zone in the classrooms. The developed daylighting system was evaluated by RADIANCE program in terms of illuminance levels and uniformity improvement across the classrooms for different sky conditions and different building orientations.