Biological systems are characterized by presence of large, complex biological molecules arrayed as collections of genes, transcripts, proteins, carbohydrates, lipids, and associated metabolites. Whereas a comprehensive chemical definition of biological systems was once beyond the realm of possibility, we can now envision the treatment of biological cells, tissues, and even complete organisms in terms of their chemical composition and interactions. Bioanalytical chemistry comprises the techniques and instrumentation necessary to separate and analyze the chemical composition of biological systems. Bioanalytical chemists have already made tremendous contributions in the areas of genomics, gene expression analysis, and disease gene/protein identification, as well as drug discovery and forensic science. In addition to further contributions in these fields, bioanalytical chemists will be increasingly needed to improve the practice of medicine through chemically- defined diseases states, and to protect our general public through surveillance for illicit drugs, explosives, and pathogens. The track in bioanalytical chemistry is built on the foundations of chemical biology. After the first two years in the regular chemical biology program, the bioanalytical chemistry student begins concentrating on analytical techniques relevant to biological macromolecules such as mass spectrometry, magnetic resonance imaging, flow cytometry, and genome and transcriptome array analysis.