To assess the prevalence of the Human ImmunodeficiencyrnVirus (HIV) infection, the risk factors involved and thernassociation between HIV and Sexually Transmitted Diseases (STDs),rna cross - sectional study was conducted among highschool andrncollege students attending three clinics for STDs in Addis Ababa.rnOut of 324 samples studied, 63(19%) were positive for antibodies tornHIV by Enzyme linked immunosorbent assay and Western Blotrnanalysis. Among 214 students with STDs, 48(22%) were positive forrnHIVantibodies. The seroprevalence rate for male students was 19%rn(95% confidence interval, 14 to 26) and for the female students 22%rn(95% confidence interval, 18 to 36). In addition, among 110rnstudents without STD manifestations (controls), 15(14%) werernpositive for HIV antibodies. Among these, the seroprevalence raternfor male students was 7% (95% confidence interval 1 to 13) and forrnthe female students, 25% (95% confidence interval, 12 to 38). Inrnboth STD and non - STD smaples, highschool students had a higherrnrate of HIV seropositivity than college students. Students withrnSTDs were more likely to be HIV seropositive than those without STDrnmanifestations. A current diagnosis of syphilis was associatedrnwith HIV seropositivity among the total population of studentsrn(odds ratio, 2.6; P < 0.00003); among the STD samples (odds ratio,rn2.2; P < 0.009); among total female students with STDs (odds ratio, 6.93; P < 0.002) and among total highschool students with STDsrn(odds ratio, 2.25; P < 0.01). A current diagnosis of chancroid wasrnassociated with HIV seropositivity among the totai population ofrnstudents (odds ratio, 2.0; P < 0.01) and among male students withrnSTD cases (odds ratio, 2.38; P < 0.05). Mul tipartner sexualrncontacts, lack of condom use, past STD history and current ST~rncases were found to be the risk factors for both syphilis and HIVrnsignif icantly, indicating that they are likely to be importantrnconfounders and also indicating that the association between HIVrnand syphilis can be influenced by these factors. The study findsrnthat HIV infection is present in highschools and colleges in AddisrnAbaba at high rates and STDs usch as syphilis and chancroid arernassociated with HIV transmission among the students.