Serum lactate dehydrogenase (LDH) can be a clinical marker for assessment of the severity and clinical course of atopic dermatitis (AD). One hundred twenty-eight patients with AD who visited Hirosaki University Hospital were included in this study. There are positive correlations between LDH and IgE, thymus and activation-regulated chemokine (TARC), and eosinophils, while TARC and eosinophils are used in evaluating type I-allergic disease, especially AD, and it is considered that LDH is also useful for evaluation of the severity of AD.