Osteosarcoma incidence rates in the United States peak in adolescence and in the elderly. The international patterns of osteosarcoma incidence in children have been described, whereas those for young, middle age or elderly adults have not. Using the Cancer Incidence in Five Continents, International Agency for Cancer Research database we compared incidence rates for children and adolescents (age 0-24 years), the middle age group (25-59 years) and elderly (>or=60 years) persons by world regions and individual countries. Overall, worldwide osteosarcoma incidence rates were quite similar in the younger age groups. The greatest variation in incidence rates was observed in the elderly.