The role of biogenic agents in occupational and environmental diseases has in the past several years become a topic of increased interest among health assessors. A major problem in assessing biogenic substances is a lack of standardized methodologies. Recently the American Industrial Hygiene Association (AIHA) published guidelines for sampling biological contaminants (Dillon et al. 1996). This paper will review the guidelines for different biogenic substances and its application to different environments with organic dust.