Although HIV transmission among Namibian in-school adolescents is mainly heterosexual, previous data on sexual activity are not disaggregated, making It difficult to target interventions. This study conducted a disaggregated analysis of coital activity and explored various factors associated with coital activity among Namibian High School students. A cross-sectional survey was carried out in 18 schools located in six education regions. Data were collected from 829 students through a structured questionnaire. Pearson i analysis was used to determine the distribution of coital activity for students from different regions, rural-urban areas, ethnic groups, and gender. Factors associated with coital activity were established by the use of odds ratios and multivariate logistic regression analysis. Overall, 50.2% of the students never had sex before and 29.2% were sexually active. Pearson i analysis showed that coital activity was significantly high among students In the Caprivl region, urban areas, Lozl, Herero and Damara-Nama ethnic groups, and male gender. Multivariate logistic regression showed that the only significant factors positively associated with coital activity were Herero ethnlcity, male gender, testing for HIV, thinking one could not get HIV if they were faithful to a single sexual partner, having a boyfriend of girlfriend, and drinking beer. These disaggregated results will help design targeted HIV/AIDS preventive programmes for High School students In Namibia. This can be done by targeting messages that reduce students' coital activity by way of altering personal, peer, and social behaviours.