Purpose: The purpose of this study was to determine the knowledge of nocturnal emissions, or wet dreams and to provide information for developing a wet dream education program for elementary school boys. Method: The research design was a descriptive study through questionnaires. Data was collected from May 10, 2009 to May 20, 2009. A total of 197 late elementary school boys in Incheon, Korea participated in this study. Data was analyzed using the SPSS WIN 15.0 program. Result: The results of this study were as follows; Knowledge of wet dreams in late elementary school boys was low; The mean of the information about wet dreams was 14.00 on a 100 point scale; There were significant differences of knowledge regarding wet dreams according to the educational experience at 6 items and wet dreams experience at 12 items of total 21 items. This indicates that present education for wet dreams is not efficient and does not provide appropriate information when they need practical information. Conclusion: Self education learning program for wet dreams should be developed for late elementary school boys which includes different contents and time required for further study, evaluation and assessment.