OBJECTIVE: In Tanzania female youth are increasingly becoming at greater risk of sexually transmitted HIV infection, whereby more than 80% cases occur through un-protected sex. The objective of this study was to examine related-factors which influence female students to have risky sexual contacts with casual partners including condom use and sex with sugar daddies. METHODS: A cross section study involving face-to-face interview was conducted regarding sexual behavior among 219 sexually-debuted female students aged between 18 and 24 years who were attending high schools and colleges in Dar-es-salaam, Tanzania. RESULTS: Eighty-three percent had at least one boyfriend in the past 12 months, 57% had engaged in sex with a "sugar daddy", and 24% had engaged in sex with a casual partner other than a sugar daddy. Sixty-nine percent had ever used a condom, and 66% had used a condom during their most recent sexual encounter. Thirty-two percent reported always using a condom during sex with their boyfriends, whereas only 2% always used a condom with a sugar daddy. Decision-making about condom use during sex with boyfriends was made by couples together (48%) or by the girls alone (34%), whereas the decision during sex with a sugar daddy was predominantly made by the male partner (79%). Data were analyzed using Statistical Package for Social Sciences (SPSS) version 9.5 for frequencies, cross-tabulations and chi-squired test and statistical significance set at p<0.05. CONCLUSION: The study highlighted risk factors for female students towards HIV infection. Receiving money and/or presents were the major motivations for having sex irrelevant with types of sex partners. Although most female's students disagreed in principle to have sex in exchange for money or presents, sex with sugar daddies was common among female students and was a major risk factor for HIV infection. Based on the findings, recommendations for improvement in prevention programs among female youth within Tanzanian context are discussed.