Background: Young people between the ages of 15 and 24 years are both the most threatenedrnglobally, accounting for half of all new cases and the greatest hope for curving the epidemic ofrnHIV/AIDS. Young populations, especially never-married sexually active females have therngreatest risk of HIV infection. They may not be aware of their vulnerability to it or of how bestrnto prevent it. There is a great gap between knowledge and practice which needs detailed researchrnthat address determinants.rnObjective: To assess female college studentâ€™s knowledge, sexual behavior, risk perception andrndeterminants of protective behavior of STIs/HIV/AIDS in Debre Markos town.rnMethods: A descriptive cross-sectional institution based survey was conducted from February tornApril, 2010 and was complimented by qualitative study.rnResult: 340 students interviewed and four focus group discussions were conducted. Studentsâ€™rncomprehensive knowledge was (15.5%). Only 7.4% perceived risky sexual behavior that canrnexposed them for HIV. Among the study subjects 25% were sexually active. Sixty percent of thernrespondents had used condoms consistently during their last sexual exercise. Ten percent ofrnnever married respondents had experienced sexual intercourse. 75.4% did not used condomsrnduring their last sexual contact. Of all participants 61% of the study group had ever tested forrnHIV in the last 12-months. Among those respondents who had sexual intercourse in the last onernyear 6.8% had symptom of STI as foul smelling genital discharge and/or genital ulcer. Thirteenrnpercent of respondents had ever forced by their sexual partners and 5% of sexually activernstudents had more than one sexual partner.rnConclusion: Though awareness of HIV/AIDS/STIs among female college students wasrnrelatively high, they had low comprehensive knowledge that capable of them to preventrninfections of STIs and HIV. Regarding risky sexual behavior and self risk perception, most of thernstudy subjects had involved in risky sexual behaviors but the great majority of them consideredrnthemselves having low or no risk for HIV infection. Protective behavior such as utilization ofrncondom use was found to be inadequate but self recognition of HIV status in the last 12 monthsrnwas relatively higher.rnRecommendation: Continuous IEC/BCC intervention programs paying attention on thernmisconceptions and protective behaviors against HIV/STIs; creating a positive youth friendlyrnenvironment to address sensitive gender-related issues and access protective means like condomrnprovision within the institution and the community; Emphasis should be given to ensure accessrnVIIIrnfor young people to sex education, HIV/STIs, including information about contraceptives.rnStudents have to be further promoted to HIV counseling and testing services.rnKey words: Sexual behavior; Risk perceptions; protective behavior; HIV, AIDS and STIs.