Quantitative two-site monoclonal antibody (MAb)-based enzyme-linked immunoassays for two cockroach (CR) allergens, Bla g I and Bla g II, have been developed and used to measure allergen levels in house-dust samples. Dust collected from the CR-infested homes of two patients with asthma from Charlottesville, Va., demonstrated wide variation in the levels of Bla g I, depending on the location of dust collection. Dust from kitchen floors and cabinets contained 50-fold more allergen (mean, 10,755 U/gm of dust) than dust from bedrooms and upholstered furniture (mean, 204 U/gm). One hundred forty-five dust samples were collected from the bedrooms and living rooms of 22 children with asthma and 16 control subjects without asthma living in Atlanta, Ga. Twenty-seven of the 38 homes (17/22 children with asthma; 10/16 control subjects) had detectable Bla g I (4 to 1340 U/gm of dust). Bla g II levels were assayed in 40 kitchen, bedroom, and living room samples from homes in Wilmington, Del. Highest levels of Bla g II were detected in kitchen-floor dust (300 U/gm of dust). Additionally, approximately 20% of homes with no visual evidence of CR infestation had significant levels of Bla g II in at least one dust sample (greater than 4 U/gm of dust). Our results demonstrate that CR may be an occult allergen in homes. The kitchen appears to be the primary site of CR-allergen accumulation, but significant CR-allergen levels can also be found at other sites in the home. The MAb-based assays can be used for quantitation of environmental exposure to CR allergens.(ABSTRACT TRUNCATED AT 250 WORDS)