Background: Contraceptive methods (CM) are important resources in the prevention of adolescent pregnancy. This study aimed to investigate adolescent knowledge, attitudes and practices related to contraception. Study Design: A cross-sectional and exploratory study was conducted with 7th to 9th grade adolescents in northeastern Brazil. Their knowledge, attitudes, and contraceptive method use were analysed by gender, age and sexual initiation groups. Results: A sexual debut had been experienced by 21% (n = 120) of all respondents (n = 570). The majority of the respondents who had experienced a sexual debut were male (73.3%, n = 88), their mean age was 15 years (SD = 1.46), and 49.3% (n = 59) never used any CM. The participants displayed low knowledge and unfavourable and ambivalent attitudes concerning contraception. Conclusion: Adolescents initiate sexual intercourse with knowledge and attitudes that limit the use of CM, which makes them more at risk of pregnancy. Further research that will be representative of the specific population in need of interventions is necessary.