To investigate the role of bacteria on facial rosacea-like dermatitis lesion in adult type atopic dermatitis, we measured the numbers of bacteria on the skin, nasal and pharyngeal surface of each individual, and then examined its sensitivity to antibiotics. The numbers of bacteria on the surface of skin increased according to the severity of skin eruption. Staphylococcus aureus was detected from the skin and nasal surface more than pharyngeal surface. Bacteria on the pharyngeal surface were both staphylococcus aureus and haemophilus parainfluenzae. Therefore, it is suggested that bacterial flora on the pharynx is different from those of the skin and nose. The treatment with antibiotics was effective for exudative lesions, whereas lichenified lesion did not respond to antibiotic therapy. These results suggest that bacteria on the skin surface are one of precipitating factors of the rosacea-like dermatitis of atopic dermatitis.