Ethiopia is a developing country with a demographic profile dominated by a young population. Due to biological, psychological, socio cultural and economic factors, young people, particularly those aged 15-29 years, are generally at a high risk of HIV/AIDS and other reproductive health problems. This paper presented results of a cross-sectional descriptive study conducted in Bahir Dar Town, northwest Ethiopia, to assess sexual behavior and risk perception of HIV infection among youths .Both quantitative and qualitative method of data-collection methods were employed to conduct the study. For quantitative data collection, a household questioner survey was conducted among 232 youth, aged 15-29 years, within the 4kebeles (villages) of the town. Qualitative data were collected by conducting focus-group discussions and in-depth interviews with 17 participants. Descriptive statistics was used to characterize socio-economic, demographic and behavioral variables and the level of risk perception of HIV. Chi-square was used to examine the association of socio-economic, demographic and behavioral variables to HIV risk perception. Logistic regression model was used further examined to identify the prediction independent variables to risk perception. Data obtained by interview and focus group discussion were qualitatively analyzed. The minimum mean age at first sexual commencement was 16.71(+1.45) years and the maximum is 26.25(+1.18).Socio-economic and demographic variables such as Job(x²=4.7151, p=0.03), alcohol use(x²=16.8405, p=0.001), monthly income(x²=12.769,p=0.026), gender(x²=9.4788, p=0.002) and education status(x²=11.8883, p=0.003) were significantly associated with risk perception of HIV among the youth. Behavioral variables such as sex ever had (²=10.1561,p=0.001), age at first sex (x²=7.524, p=0.023), no of sexual partners(²=7.2156, p=0.002 and knowledge of HIV status(x²=16.0624, p=0.000) were also significantly associated with risk perception of HIV among the youths. IN logistic regression model, age (z=-2.13, p=0.033), education status (z=-4.36, p=0.000), marital status (z=-2.48, p=0.013), alcohol use (z=4.88, p=0.000), and knowledge of HIV status (z=-3.69, p=0.000) were significantly and independently predicted HIV risk perception. In conclusion, further research should be conducted to better understand the nature of association between the above socio-economic and demographic, and sexual behavioral variables with risk perception of HIV/AIDS Staking behaviors. Keywords: sexual behavior, risk perception