In western populations, the annual incidence rate of cancer among adolescents aged 15-19 years is around 150-200 per million, intermediate between the rates for older children and young adults. The most frequent diagnostic groups are acute leukemia, lymphomas, central nervous system tumors, bone and soft tissue sarcomas, germ cell tumors, thyroid carcinoma, and malignant melanoma. While the causes of most cancers in teenagers are still unknown, health education and promotion and public health programs offer some scope for prevention among people of this age group. Reduction in sun exposure should lead to a reduction in incidence of melanoma, and elimination of hepatitis B in regions where it is endemic should result in a decrease in hepatic carcinoma. Five-year survival of patients diagnosed around 1990 exceeded 70% in the USA and UK. Entry to clinical trials appears to be much less frequent for adolescents with cancer than for children. There is some evidence that higher survival is associated with entry to trials or centralized treatment for certain cancers in this age group.