Background: Various techniques have been tried in an attempt to reduce allergen levels in homes. This study investigated the effect of dry heat on mite, cat, and dog allergens. Methods: Samples (50 mg) of Dermatophagoides pteronyssinus and D. farinae cultures, and of house dust rich in the major cat and dog allergens Fel d 1 and Can f 1 were heated for 5, 10, 15, 30, and 60 min at 60°, 80°, 100°, 120°, and 140°C. Control samples remained at room temperature. Extracts were assayed with the appropriate two-site mono- or mono/polyclonal sandwich ELISA. Results: For Der p 1, the breakdown was proportional to temperature and heating time; after 30 min at 120°C, allergen levels were reduced to <1% of control. Der p 2 was more heat stable, requiring 140°C for 30-60 min to achieve > 99% reduction.D. farinae groups 1 and 2 allergens showed results similar to those obtained with D. pteronyssinus. In contrast, Can f 1 and Fel d 1 were considerably more thermostable, with 50% and 70%, respectively, of allergen remaining after 60 min at 140°C. Conclusions: The effect of dry heat on allergens increased with increasing time and temperature, cat and dog allergens demonstrating greater heat resistance than mite allergens. Dry heating methods may represent an alternative technique for removal of mite allergens; however, the greater stability of Fel d 1 and Can f 1 suggests that this procedure may not be appropriate for pet allergens.