The investigation of occupational asthma requires the detection of both viable and nonviable allergen-bearing particles. Isolation and enumeration of microorganisms can be achieved using filter aerosol monitors, liquid impingers, Andersen cascade impactors, and other samplers. Detection of defined allergens can be achieved only through immunoassay of samples collected, for example, by filtration, impingement, or electrostatic precipitation. Collection and extraction methods have been compared using radioallergosorbent test (RAST) inhibition and enzyme-linked immunosorbent assay (ELISA). Coca’s mineral salt solution extracted fly antigen better than citrate borate buffer and phosphate buffered saline, but best recovery of egg albumin was obtained with ammonium bicarbonate. High-volume filtration samplers yielded less allergens than large-volume Litton-type electrostatic samplers which collected into liquid. Recovery on dry filters decreased with time of sampling suggesting adsorption of allergens onto the filter or its denaturation through dehydration. Yields of airborne scampi protein, measured by ELISA, were almost 20 times greater in samples collected by electrostatic precipitation than by filtration and only the liquid samples yielded allergens detectable by RAST.