The relationship between psychological state and skin lesions of atopic dermatitis were investigated with a 31-year-old male patient. He had severe atopic dermatitis which became worse with psychological stress. A psychological test, profile of mood states (POMS), was performed on him every 2 weeks. Peripheral lymphocytes and natural killer (NK) cell activity were investigated at some points. When the psychological state showed more depressive, anxiety, anger, fatigue and confusion, the skin lesions became worse and recovered after the psychological states turned well. Correlation was shown between itch and stress or fatigue by a visual analogue scale (VAS) (p < 0.001). NK cell activity decreased during the worse psychological state and recovered during the near normal psychological state, although, the lymphocyte count and CD4/8 ratio in peripheral blood did not change during the study. These results suggest that some patients with atopic dermatitis should be treated psychologically in addition to standard dermatological treatment.