Background: Atopic dermatitis of the head and neck (HNAD) has been recognized as a separate entity. Malassezia furfur, a lipophilic yeast, is considered to be a pathogenic allergen in this form of atopic dermatitis. Objective: The purpose of this study was to determine the level of IgE anti-M.-furfur antibodies and their relation to the severity of the disease. Methods: IgE anti-M.-furfur antibodies were assayed in 106 patients with HNAD. Controls included 25 patients with non-HNAD, 20 with nonatopic dermatitis and 16 with seborrheic dermatitis (including 4 with AIDS). Results: There was a highly significant correlation between the level of anti-M.-furfur IgE and clinical severity. Furthermore, there was a significant but smaller correlation between total IgE and clinical severity. In patients with HNAD, total IgE was higher amongst men. Conclusion: IgE anti-M.-furfur antibodies are a good and specific marker for HNAD. IgE M. furfur levels are strongly correlated with the severity of the disease.