This paper focuses on recent developments of biofiltration technology used in treating nuisance chemical odors from industrial and municipal air streams. In the biofiltration process, odorous chemical constituents in the air are first transported to biofilms by diffusion, solubilization and adsorption processes. Bacteria within the biofilms oxidize odor constituents into harmless and odorless products. Through successful laboratory and pilot research on biofiltration of odorous air-stream constituents, numerous commercial biofilters have been designed and installed across North America. In this paper, case studies related to biofiltration of air emissions from meat rendering plants, municipal wastewater treatment applications, and printed circuit board production are discussed to demonstrate the robustness of this technology in eliminating a wide variety of compounds.