A survey was conducted on 2,321 Chung Rhang Middle School boys to check out their physical growth, development and the number of parasite carriers during the period from June 16. to June 23. 1970 As the results of this study, the following conclusions were revealed. A) Physical Growth and Development State. 1. Direct curve in physical growth and development was observed during the period from 13 to 16 years of age. 2. The age and quantity of maximum growth and development. Height; 13~14 years of age 6.1cm Body weight; 14~15 years of age 5.1kg Chest circumference; 13~14 years of age 9.9cm Sitting height; 14~15 years of age 3.4cm 3. Comparison with Japanese students Most Korean students are shorter than Japanese students, though the standard of height became higher than before. The standard of body weight is visibly lower than Japanese students. The standard of chest circumference of the students of age 14 is higher than counter part of Japanese students and the all boys are lower than Japanese students except at the age of 14. The standard of the sitting heights of the Korean students are growing steadily, but every students are shorter than Japanese students. 4. The greatest differences in physical growth and development were shown in 13~14 years of age. 5. The students of 13~15 years of age developed their bodies most highly according to index of Rohrer. 6. Body weight and chest circumference have not grown enough compared with height. The development of sitting height was made highly and the development is steadily growing as they grow old. B. The Number of Parasite Carriers The number of parasite carriers was shown 79.4 per cent among all the student checked out. The number of trichuris was shown 79.7 per cent. The number of parasite carriers was shown higher per cent as the grow old.