The major purpose of this research was to investigate the pattern of sexual behavior and practices of highrnschool youths in Addis Ababa administrative region. The main issues considered were sexual orientation,rntype of sex practices, sexual partner, condom use, sexual debut, substance use or abuse, knowledge,rnattitude and perception of HIV risk and sexual abuse or harassment.rnSince the topic is sensitive and touches individuals' private issues, descriptive survey study methodrncomplemented by qualitative study was employed so as to get reliable information. In addition to thernquestionnaire, focus group discussion has also been used. Besides, in-depth interview was also used forrngay and lesbian students who have been accessed through snow ball technique. The information obtainedrnfrom the questionnaire was analyzed using statistical tools of percentage and mean using computerrnassisted Ms- SPSS program, version 12. This statistical tool has been chosen because the research mainrnfocus was only to describe the sexual behavior of youths.rnSome of the major findings include 34.6% of the high school students were sexually active though the typernof sex practice was varying. The study found out that 11.6 % and 19.1 % of the respondents practice analrnand oral sex respectively. Masturbation was also another type of sex practice commonly reported by thernhigh school students.rnHigh school youths had two and more life time partner for vaginal sex and it is about seven for anal sex.rnCondom use was negligible among high school students with 19.7 % for vaginal, 3.5% for anal and non-forrnoral sex. 41.1 % and 12.6 % sexually active respondents reported that they were sexual abused andrnharassed at home and in school respectively.