The discovery that DNA sequence variations can influence the response of an individual to a drug or can predict the outcome of a disease has added a new dimension to evidence-based medicine. It is clear that the goals, risks, and benefits of drug therapy can be better assessed if the underlying genome of the patient is known. The relevance of identifying patients at increased risk of adverse drug reactions, the application of genomic technologies to drug development and the clarification of the mechanisms of drug action on cells will be important targets in the therapeutic approach to medicine in the 21st century. In this review, we summarize the development of single nucleotide polymorphisms (SNPs) and give computational biological data for SNPs databases.