Low-income housing often has multiple indoor health risks. Among them, pest infestation, pesticide use, and pest allergens are recognized as common risks which affect residents' health. Cockroach and rodent allergens are associated with morbidity and mortality of asthmatics. To characterize the levels of pest infestation, residents' attitudes toward pest control, and the relationships among cockroaches, mice, cockroach allergen level, asthma and allergy rate in public housing, we interviewed residents from 358 randomly selected apartments in Gary, Indiana and assessed the environmental conditions. Dust samples were collected from 101 apartment kitchen floors to analyze for cockroach allergen (Bla g 1 and Bla g 2) levels. Eighty one percent of the apartments were found infested by cockroaches, mice, ants, spiders, or flies. In the 101 apartments evaluated, 98% of the kitchen dust samples had detectable levels of Bla g 1 allergen (>or=0.4 U/g), 52% had >or=2 U/g, and 33% had >or=8 U/g of Bla g 1. Among the 1,173 residents, 13% and 9% had physician-diagnosed asthma and allergy, respectively. Existence of diagnosed asthmatic was positively correlated with mouse infestations.