Problems of birth defects and low birth weight are important issues of public health because most infant mortality are caused by these two. To discover the etiology of birth defects and low birth weight, it is necessary to establish epidemiological birth defects monitoring system in Korea. With the rapid growing of internet usage in korea, the computer network has become the popular means of communicating and sharing of information. Our aim was to develop web-based reporting and database management system in Incheon to establish birth defects monitoring system to evaluate the incidence rate and patterns of birth defects in Korea. Public health center and private hospitals and clinics participated in this monitoring system. Web based reporting system have been built and operated during 2 years (first year: December 1st, 1998-November. 31, 1999; second year: January 1st, 2000 - December 31th, 2000). Trained nurses actively collected the records obtained from delivery units in the participating hospitals. During first and second year, the incidence rate of birth defect per thousand person was 10.0 and 8.0 respectively. In conclusion, we could build web-based monitoring system for birth defects successfully in Yonsu gu, Incheon. It could be a model of national standard for population-based monitoring system for birth defects in Korea.