The study on knowledge of non-consensual sex among senior secondary school students in Rivers State was conceived due to the fact that secondary school students in Rivers State being within the age of development of secondary sexual characteristics have minimal knowledge of non-consensual sex. This study investigated the knowledge of non-consensual sex among senior secondary school students in Rivers State. One research question and two null hypotheses guided the study. The study adopted the descriptive cross sectional survey design. A sample of 1,600 senior secondary school students was selected for the study using multi-stage sampling procedure. The questionnaire titled “Knowledge on Non-consensual Sex instrument” was used for data collection which had reliability index of 0.85 via Kuder-Richardson 21 method and was validated by 5 experts in reproductive health, sex psychology, public health and statistics. Summation scores, ANOVA and z-test were used to analyse data. The findings of the study were that 59%(748) of the respondents had poor knowledge of non-consensual sex, there existed no significant difference in mean scores of students’ knowledge of non-consensual sex based on age (p>0.05) at 2df, and that knowledge of non-consensual sex was not significant based on gender (p<0.05) with the male having more knowledge of non-consensual sex than their female contemporaries.