The Internet offers a number of resources to clinical geneticists. This review outlines some of these with special emphasis on sites present at the National Center for Biotechnology Information (NCBI) at the National Library of Medicine at the National Institutes of Health. Special attention is presented on how these various resources make use of PubMed, the premiere source of MEDLINE information on the Internet. Three NCBI resources are presented here. 1) 'Genes and diseases': a general curated series of web pages outlining various references to known genetic diseases with links to relevant on-line resources. 2) The Online Mendelian Inheritance in Man (OMIM) from Victor A. McKusick at Johns Hopkins University presents our current knowledge of all known human genetic diseases. 3) Human genome resources describe our current knowledge on the human genome project (HGP). A list of relevant uniform resource locators (URLs) is also included.