Objective: This study investigated access to and use of reproductive health information among in-school adolescent girls in Lagos State, Nigeria. Design: Descriptive survey research design was adopted for the study. Setting: The study sample consisted of 1,800 girls randomly selected from 18 public senior secondary schools in Lagos State. Method: Data were collected with a questionnaire. Descriptive and inferential statistics were used for data analysis. Result: Parents were the most accessible source of reproductive health information while the Internet was the least accessible. More than 50 per cent of the respondents were not using reproductive health-related information regularly. There is no statistically-significant difference in access to and use of reproductive health information among girls in single sex and co-educational schools in Lagos State, Nigeria. Conclusion: The National Comprehensive Sexuality Education Curriculum should be implemented in all the secondary schools in Lagos State and elsewhere in Nigeria. Access to and use of reproductive health information should be promoted through regular workshops, seminars, symposia, lectures and talks for parents, teachers, and students. (Contains 6 tables.)