Sexuality education in the period of adolescents need much care and attention. The programs of sexual education through the Internet are excellent resources for adolescents to gain the information related to their sexual health. And systematic program which is necessary for adolescents to manage their sexual health has been rarely found in Korea. The purpose of this study was to offer valuable database for program design and evaluation on sexual education of middle school students through the Internet. Needs assessment for the information of sexual education on the internet among middle school students were carried out. A questionnaire survey was conducted with respondents of 602 middle school students from January to March in 2002. In the sexual counseling center for middle school students, counseling cases through internet were analyzed and evaluated from October, 2001 to September, 2002, We have selected 16 Sexual educational websites in Seoul confirmed Korean Educational Human Resource. Contents which was illustrated in 16 sexual educational websites were analyzed and evaluated by 12 sexual counselors. Design and evaluation of the program on the internet for sexuality education of adolescences was conducted on the basis of this study results by middle school expert teachers, sexual counselors, sexuality education professionals. Data was statistically analyzed using dBSTAT 4.0 for Windows.The extent and phase of the teaching-learning program of the sexuality education on the internet was seen as follows :1. We evaluated to need for sexuality education on the internet by middle school student.2. We assessed the properness of sexuality education curriculum on the internet frequently used by middle school students.3. We designed teaching strategy and learning program for sexuality education of the middle school students. 4. We developed the assessment method for the teaching-learning program of the sexuality education in adolescences on the internet.Middle school students responded that sexual education through Internet is needed in the order of programs related to acquaintances with opposite sex, Sexual culture and ethics, Sexual health, Reproductive health structure and development, Marriage and family, Psychology of Sexuality, Pregnancy and birth. In the internet counseling, cases on the 'reproductive health structure and development' was ranked as the top. In short we have found the most needs as follows; Meaning of the marriage life and having family, Sexes and Love, Human relation, Sexual Culture.We recommend as follows on the basis of this study results: 1. It is necessary for sexuality education program on the internet to specify acccording to age and target the specific individual needs. 2. Sexual educators have to employ various educational materials such as flash, cartoon, multimedia in order to provide effective sexuality education. 3. Internet based sex education need to be evaluated regularly through reassessment of the effectiveness of sexuality education for content quality and richness.