Malignant bone tumours in children are rare, accounting for approximately 5% of all childhood cancers in European countries. In the EUROCARE childhood cancer study, there were 1785 registrations from 16 countries for bone cancers in patients aged 0--14 years during 1978--1989. Of this total, almost three-quarters were contributed by childhood cancer registries in Germany and the UK. Estimated 5-year survival rates were 52% for osteosarcoma and 50% for Ewing's sarcoma over the entire study period and 60% for both diagnostic groups in 1985--1989. For osteosarcoma, survival rates increased substantially until about 1985, but then showed no further improvement. For Ewing's sarcoma, there was a steady increase throughout the study period. Improvements in survival which had previously been reported from individual countries and in clinical series are confirmed as having taken place throughout much of Europe on a population basis.