Cancer is an under-emphasised issue in Africa, partly because of the overwhelming burden of communicable diseases. However cancer is a common disease in Africa with 650 000 people, of a population of 965 million, diagnosed annually. Furthermore, the lifetime risk in females (between 0 and 64 years) of cancer is about 10%, which is only about 30% lower than the risk in developed countries. In females, the lifetime risk of dying from cancer in Africa is almost double the risk in developed countries. This Review is the first of two papers and focuses on the current knowledge of the distribution and trends of the most common cancers in Africa. The cancers with the highest incidence are cervical, breast, and now HIV-associated Kaposi's sarcoma. The top five cancers in males--Kaposi's sarcoma (constituting 12.9% of all cancers in males) and cancer of the liver (14.8%), prostate (9.5%), bladder (6.1%), and non-Hodgkin lymphoma (5.7%)--and in females--cancer of the cervix (constituting 23.3% of all cancers in females) and breast (19.2%), Kaposi's sarcoma (5.1%), cancer of the liver (5.0%), and non-Hodgkin lymphoma (3.7%)--are discussed in detail. The second paper will focus on the causes and control of cancer in Africa. The cancer burden in Africa is likely to increase as a result of increases in HIV-associated cancers, changes in lifestyles associated with economic development, and the increasing age of the population (despite AIDS). Although the knowledge of cancer in this region is improving, better surveillance of cancer incidence, mortality, and prevalence of risk factors is urgently needed to monitor the development of the cancer epidemic, formulate appropriate cancer-control strategies, and assess the outcomes of these strategies.