We used the nation-wide Swedish Family-Cancer Database to examine the familial risks of histology-specific bone cancers in offspring by parental or sibling probands. Adjusted standardised incidence ratios (SIRs) were used to measure the risk. Among the 1327 offspring bone cancers, only two parent-offspring pairs and one sibling pair were noted with concordant bone cancer but the SIRs were not significant. Significant associations were observed in specific histological types or specific age groups, some of which may be chance findings arising from multiple comparisons. However, the risk of early-onset (< 25 years) osteosarcoma in offspring was significantly increased when mothers presented with breast cancer (1.7) and melanoma (2.9), suggesting that Li-Fraumeni syndrome could partly explain this familial aggregation. Other associations, such as childhood osteosarcoma with parental liver cancer, Ewing's sarcoma with kidney cancer and giant cell sarcoma with maternal breast cancer, were novel findings and may be related to other familial diseases.