BackgroundReproductive health services in the form of adolescent health and contraceptive services are fundamental in the prevention of a high incidence of teenage pregnancy. The purpose of this study was to determine the age at menarche, menstrual pattern, and awareness of and use of modern contraception among secondary school girls in Abakaliki, Nigeria.Subjects and materialsThis was a cross-sectional study in which self-administered questionnaires were completed by 482 adolescent girls at two girls’ secondary schools between August and September 2012.ResultsThe mean age at menarche was 13.13±1.37 years. The mean menstrual cycle length was 27.8±3.14 days, and the mean duration of menstrual flow was 4.8±1.14 days. Thirty-seven (7.7%) respondents were ignorant of their cycle length, while 29 (6.0%) had irregular cycles. Premenstrual syndrome and dysmenorrhea were major menstrual issues, which resulted in 69 (14.3%) and 59 (12.2%) of respondents resorting to self-medication and absenteeism from school, respectively. Mothers were the main source of their daughters’ adolescent education, while friends and mass media were the main source of contraceptive information. Though there was a high level (75.7%) of awareness of contraceptive information among the girls, usage (8.9%) was poor. Only eight (18.6%) of the 43 respondents who had ever used modern contraception were adherent to modern contraceptives. Students who were more than 15 years old, attained menarche at 13 years or less, and whose families were of low socioeconomic classes were more likely to be sexually active.ConclusionThe declining age at menarche, menstrual challenges, and poor reproductive health status of adolescent girls in this study have made menstrual issues and contraceptive adherence critical aspects of adolescent health care, especially when appropriate sources of reproductive health information were not fully harnessed. Therefore, there is an urgent need to establish adolescent-friendly clinics and include sexuality education in the curriculum of schools in this environment.