Vitamin D is an essential hormone that is synthesized in the skin, it has a number of functions in addition to its well-known role as a modulator of calcium metabolism and homeostasis. It affects both the innate and adaptive immune system through its effects on T and B lymphocytes, dendritic cells, and macrophages, in dermatological diseases, it plays an important role as an immune modulator in atopic dermatitis, psoriasis, vitiligo, and alopecia. The aim of this study is to evaluate 25-hydroxy Vitamin D in female patients with late onset acne comparing their levels with female patient with acne vulgaris, and also to correlate their levels with demographic data and clinical data of the disease. This study will include 30 female patients with acne vulgaris, 30 female patients with late onset acne and 30 patients with age and sex matched healthy volunteers as control group. They are selected from the Outpatient Clinic of Dermatology, Venereology and Andrology Department of Benha University Hospitals. Vitamin D serum levels were significantly lower in acne vulgaris patients than in control. The mean VIT-D serum levels were non-significant difference between late onset acne patients and their controls. Vitamin D deficiency may play an important role in the pathogenesis of acne vulgaris. Vitamin D supplements could be a helpful adjuvant in the treatment of acne vulgaris.