The evaluation and control of objectionable odors in the workplace appears to be an increasing challenge for the industrial hygienist. People working in a relatively clean environment often respond adversely to odors, and hence, the industrial hygienist may be called upon to identify the sources and offer means to correct the situation. The resolution of odor problems can be especially problematic because of a number of factors. Odors are often mixtures of several chemically discrete substances that are present at very low concentrations. Individuals also vary widely in their response to odors. Biological agents are a potential source of objectional odors. Three case studies are presented in which a common bacteria was isolated and appears to be a probable source of the odor. Analysis of the air in the affected area indicated the presence of 2-methyl proprionic acid and 1-butoxy-2-propanol, which have odors that are usually characterized as offensive. A laboratory test of the air over a pure culture of the bacteria was also positive for 1-butoxy-2-propanol.