Background Vitamin D is a fat-soluble vitamin and synthesized in the skin from 7-dehydroxy cholesterol during exposure to ultraviolet B. Vitamin D is essential for calcium homeostasis, bone growth, and immune regulation. Vitamin D deficiency causes rickets, osteomalacia, osteoporosis, and muscle weakness. Vitamin D deficiency is associated with cancers, cardiovascular diseases, schizophrenia, wheezing illness, and autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes mellitus, multiple sclerosis, Crohn’s disease, psoriasis, vitiligo, and chronic urticaria. Objective The main objective of this study was to analyze the 25-hydroxy vitamin D status of patients with psoriasis in comparison with controls without psoriasis. Patients and methods This study included 30 patients (age-matched and sex-matched controls) from the Outpatient Department of Narayana Hospital Dermatology Department in Nellore, Andhra Pradesh. All patients and controls were studied during the 4-month period from July 2015 to October 2015. Results Serum 25-hydroxy vitamin D levels were significantly lower in psoriatic patients than in controls even after adjusting for confounding factors in a multivariate analysis. Low 25-hydroxy vitamin D levels were positively associated with psoriasis and BMI in multiple linear regression analysis. Psoriatic patients with BMI greater than or equal to 27 kg/m2 had a higher risk for 25-hydroxy vitamin D insufficiency. Limitations Further studies with larger numbers of patients are required to analyze the pathogenic mechanisms underlying the relationship between 25-hydroxy vitamin D deficiency and psoriasis. Conclusion The 25-hydroxy vitamin D values are significantly lower in psoriatic patients than in controls. Low 25-hydroxy vitamin D levels are positively associated with psoriasis and with obesity.