Background: Vitamin D is known to play roles in innate and adaptive immunity. There were many different studies exist on the serum vitamin D level in chronic skin diseases. Objectives: To determine if a significant difference exists between serum 25-OH-Vitamin D3 level and various chronic skin diseases. Methods: A retrospective study was conducted for the patients in our clinic from 2013.7 to 2014.7. Serum vitamin D level was measured by checking 25-OH-Vitamin-D3 RIA. Results: Six hundred thirty two disease group subjects(272 males, 360 females, age 42.02+-19.37) and 124 healthy group subjects(50 males, 74 females, age 36.52+-16.91) were included in the analysis. When the season, sex and age variables were compensated statistically, the 25-OH-Vitamin D3 level was decreased in chronic urticaria(p=0.014), chronic eczematoid dermatitis(p=0.012), vitiligo(p=0.039), herpes zoster group(p=0.001) compared with healthy control group (16.69+-11.22ng/mL). Meanwhile there was no statistical difference in atopic dermatitis, psoriasis, alopecia areata. In 217 of 632 enrolled subjects were included in analysis of multiple allergen stimulation test (MAST). The 25-OH-Vitamin D3 level in the group of elevated total IgE or antigen sensitization was not significant different from control group. Conclusion: The serum 25-OH-Vitamin D3 level might be decreased in chronic skin disease such as chronic uticaria, chronic eczematoid dermatitis, vitiligo. More detailed and controlled study is needed.