A large proportion of the millions of adolescents worldwide who are sexually active have sex without using modern contraceptives or protection against sexually transmitted infections (STI). In many cases, this results in too-early (and often unwanted) pregnancies and STI, with negative consequences at different levels. Adolescents in general--and unmarried adolescents in particular--often find it difficult to obtain the contraceptives they need. Health workers are often unaware of the special needs of adolescents, and contraceptive services are only rarely provided in a manner that is accessible to adolescents. The World Health Organization stresses that age alone does not constitute a medical reason for denying any available contraceptive method to adolescents. However, it recommends that it is important for health workers to be well aware of the biomedical, psychological and social issues that affect how they can assist adolescents in making well-informed choices of contraceptive methods that suit their special needs, and in using the contraceptives, they choose in an effective manner.