Pyrolysis-mass spectrometry, incorporating an in situ thermal hydrolysis and methylation(THM) step, has been used to study biological materials for bacteria, toxin and virus. Newly developed pyrolyzer was used to decompose biological materials, and tetramethylammonium hydroxide(TMAH) was used as a methylation reagent. Chemical ionization(CI) using ethanol and ion trap mass spectrometer(ITMS) were used to ionize and analyze of pyrolysis components, respectively. Analytical characteristics of bacteria (including spore), virus and toxin were analyzed. Also acquisition and interpretation of mass spectra as biomarkers for classification/identification of biological material s were explained.