Public health practice will not be able in the 21st century to ignore the impact of genomics, cell and molecular biology. It will need to take into consideration issues that include, among others: the complementary nature of social and biological models of disease, genetic exceptionalism, the readiness of public and patient to respond to genomic information, the relationship between individuals and populations, and concepts of population stratification. Health systems will need to adapt their practice and organisation to include new sequencing technologies, bioinformatic expertise and proper evaluation of genetic and molecular tests. Links with the commercial sector will increase in importance. The impact on developing countries cannot be ignored and will require special attention.