Pharmacogenomics is the study of the myriad interactions between genes and pharmacotherapy. Developments in pharmacogenomics have changed and will affect pharmaceutical research, drug development and the practice of medicine in a significant way. In this article, we make an inventory of the ethical implications that might arise as a result of possible developments in pharmacogenomics and investigate whether the present ethical framework will be able to adequately answer arising questions. We think that many of the questions related to the consequences of pharmacogenomics are answerable along the lines of present ethical thinking. We also believe, however, that many 'changes of degree' may result in a 'change of kind.' We therefore think that pharmacogenomics may potentially have such a profound influence on scientific research and the pharmaceutical industry, the practice of medicine and society at large, that this will generate its own unique dynamic, which will require new ethical research. We suggest that the notion of 'responsibility' will be a major focus of such research.