Occupational exposures to airborne fungi at a sugar beet refinery were studied. Personal and area air samples collected during sugar production and cleanup phases in a sugar beet refinery in Michigan were analyzed for growth of residual colony forming units. Fungi identified in the air samples included Alternaria, Aspergillus, Beauveria, Botrytis, Cladosporium, Drechslera, Monilia, Mucorales, Penicillium, Rhizopus, and Trichoderma. The predominant genera were Penicillium, Cladosporium, Aspergillus, Monilia, Trichoderma, and Rhizopus. The most contaminated area of the facility was found to be the pellet conveyor area with a spore concentration of 69,000 colony forming units/cubic meter. The highest average personal exposures were found in those working as pellet loaders during the production phase while beet washers had the lowest average exposure in this phase. A marked increase in exposure levels was seen in the postproduction cleanup phase compared with those seen in the production phase. Descriptions of several engineering controls designed to decrease exposures at this refinery were presented.