Chemical warfare agents (CWAs) are the most toxic compounds ever produced. To develop medical countermeasures against the effects of these agents, analytical procedures to analyze these agents in biological matrices are essential for a better understanding of the toxicological process. The need for the analysis of biomedical samples can have several purposes. First, the agent itself may be detected in the intact form in the case of toxicokinetic studies. Second, verification of exposure to CWAs is another goal that requires analytical methodology for biomedical samples. Most of the analytical methodologies rely on instrumental analysis techniques like liquid and gas chromatography combined with mass spectrometry. The progress in instrument development has been tremendous in the past decades, especially analyses based on mass spectrometry, which are now more or less routine. However, analyses of CWAs might need some additional requirements. For example, it might be necessary to measure an intact agent at extremely low concentrations, because only these levels are relevant in view of the high toxicity of the agents. In that case, the analytical configuration needs to be adapted to facilitate large-volume sample introduction. In this chapter, the methods for the bioanalysis of a CWA or its biomarkers will be briefly described. In a case when the instrumentation for a particular analysis is more sophisticated than a standard configuration, it is discussed in more detail. © 2015 Elsevier Inc. All rights reserved.