A survey of population-based cancer registries in the European Community (EC) is reported: 82 (924b) of 89 registries replied. In 3 of the I2 EC countries (Denmark, Netherlands, UK), general cancer registration applies to the entire population; national registration for childhood neoplasms also applies in 3 countries (FRC, Ireland, UK). About 350,000 new cancers were recorded each year during 1982-1985 in the 32% of the EC population which is covered by general registration. It is estimated that during this period about 988,000 new cancers (excluding non-melanoma skin cancer) occurred each year in the 10 EC countries for which incidence data are available. Most registries report 90-95% completeness of cancer registration, but there is evidence of imprecision in these estimates. Risk factors for cancer are recorded in 43 registries, in particular occupation (38), but recording of occupation is often incomplete. The use of international or compatible systems of coding occupation would facilitate screening of cancer registration data for occupational hazards in the European Community. The quality of cancer information in the Community would be greatly improved by the systematic and widespread use of simple methods to estimate completeness of registration and by allowing registries confidential access to death certificates. 'To whom reprint requests should be sent.