This nationally representative study, encompassing all single youth (15-24 years), was carried out on the subpopulation of Ethiopia DHS 2000 to determine the influences of socio-demographic characteristics on sexual behaviour, and assess the knowledge and awareness of HIV/AIDS and other STIs. There were a total of 890 male and 3,988 female youth. 25.5% of males and 16.1% of females ever had sexual intercourse. Among these, 65.8% males and 24.6% females had two or more sexual partners in the last 12 months. Condom use in the last sexual act was reported by 22.7% and 10% of male and female youth. 19.4% of male and 22.2% of female youth who ever had sexual intercourse ever used family planning method. Although the majority of youth is aware of HIV/AIDS, awareness about other STIs is low. On binary logistic regression analysis, the odds of ever having sexual intercourse were higher for the employed and older youth. Male urban youth was more likely to ever have sexual intercourse than male rural youth (Adjusted OR 4.2; 95% CI 1.8-9.5). Male youth with some form of education were more likely to use condom (Adjusted OR 4.9; 95% CI 1.01-24.7). Female youth with some form of education, the risk of ever having sexual intercourse was reduced by 50% but they were more likely to report having ³ 2 sexual partners in the last 12 months (Adjusted OR 2.1; 95% CI 1.1-4.1). Female youth who had media exposure were more likely to report having ³ 2 sexual partners in the last 12 months (Adjusted OR 2.9; 95% CI 1.3-6.8) but more likely to use condom during last sexual intercourse (Adjusted OR 15.7; 95% CI 2.2-117). Among single Ethiopian youth the overall sexual activity is relatively lower than reported from other African countries but high risk sexual behaviour is common. Socio-demographic factors influence youth sexual behaviour