Previous studies confirmed that lack and poor sexuality education knowledge among adolescents has exposed most adolescents to risky sexual behavior. The objective of this study is to fill the gap of lack and poor sexuality education knowledge by conducting intervention on knowledge of sexuality education while assessing knowledge level and mean score knowledge level among adolescents in selected secondary schools in Abeokuta Ogun state Nigeria. Quasi-experimental two group pre-post design was used and a sample size of 374 was chosen for the study.  Adapted UNESCO guidelines was used as sexuality education package, a validated questionnaire was used to collect data and data were analyzed using descriptive and inferential statistics. Mean score knowledge level of sexuality education on risky sexual behavior pre-post was 3.66 and 4.52 for experimental group and 3.41 for the control group pre-posttest. Mean score knowledge of sexuality education on factors associated with risky sexual behavior pre-post was 6.39 and 7.15 for the experimental group and 5.72 for the control group pre-posttest. No significant difference in the mean score knowledge level of sexuality education on risky sexual behavior pretest in experimental and control group(P>0.005) so null hypothesis was accepted. Thus, there was significant difference in the post-test mean score knowledge level of sexuality education on risky sexual behavior for experimental and control group (P<0.005) so the null hypothesis was rejected. In conclusion, sexuality education improves knowledge level of the participants. Hence, comprehensive sexuality education is therefore recommended for adolescents in secondary school to reduce the incidence risky sexual activities among them.

Keywords:     Adolescents, Knowledge intervention, Risky sexual activity, Sexuality education