This work is based on the findings of the study carried in Kilimanjaro Region about Sexual Behavior and Risk of Sexually Transmitted Diseases among Secondary school students. Data collection was done through questionnaires and interviews with the students and teachers. Findings from the study revealed that more than 50% of the respondents reported ever having sexual intercourse and about 60% of the sexually active students in both sexes reported to have never used condoms in the previous year. Both pregnancy and induced abortion had been experienced by about 12% to 27% of the sexually active female students and about 10% of the sexually active students of both sexes reported to have been diagnosed with Sexually Transmitted Diseases (STDs). The study concluded that peer influence, poverty, and relaxed parents disciplinary style are among factors which cause such behavior and recommends that sex education should be taught in secondary schools in order to raise awareness among students.