Pharmacogenetics is the study of how variation in human genes leads to variation in response to drugs. Pharmacogenomics is the term applied to large-scale genomic approaches to pharmacogenetics, and it is currently characterized chiefly by the use of high-throughput DNA sequencing to identify sequence variations in pharmacologically important genes. Genes of interest for pharmacogenomics include genes involved in drug metabolism and transport, as well as genes that are drug targets. The past year has seen an increasing number of systematic surveys of genetic variation that establish reliable baseline measurements of sequence variation--at least in coding and promoter regions. These surveys form the basis for determination of population frequencies, genetic linkage studies and association studies relating genotype with drug response phenotypes of interest.