This study addresses the influence of sex education on abortion among adolescents in schools at Gachie location of Kiambu County in Kenya. It sought to address three main objectives: determining the prevalence of abortion among adolescents; determining the importance of sex education among adolescents and examining the interventions used to mitigate against abortion among adolescents. The study employed a survey research design and used questionnaires as the main data collection instrument. The main findings of the study show that there are high prevalence rates of abortion among adolescents, there are high awareness levels about abortion, adolescents are positive about sex education and they identify it as a way of reducing abortion rates, there are few adolescents who have attended sex education sessions and finally, premarital sex was identified as the main cause of unplanned pregnancies. The study recommends greater stakeholder involvement in carrying out sex education drives, greater role of parents in educating their children regarding sex, greater role of the government in curbing the practice of abortion as well as the need for more research studies around this topic.