Concerning the maxillary, ethmoidal, and frontal sinuses from 0 to 20 years of age, we studied roentgenologically about their developments and undertook general observations about them. In this experiment, we established a unit length for measurementfor the purpose of eliminating roentgenographical errors and measuring the true development, and classified them morphologically. In consequence the characteristicsof the development of the paranasal sinuses and the correlation in development betweenthe paranasal sinuses have made clear. Furthermore some amendment is applicable to the old standard of the development in age of the paranasal sinuses.
We believe this clinically a concrete guide to the treatment and an important knowledge.