Aim: The aim of this study is to explore the relationship between vitamin D levels and antithyroid peroxidase antibodies (ATPO Ab) in recently diagnosed patients of autoimmune thyroid disease (AITD). Material and methods: A total of 138 and 30 recently diagnosed female patients of Hashimoto's thyroiditis (HT) and graves' disease (GD) along with 46 healthy females as controls were enrolled in groups I, II and III respectively. In this study 25OHD, PTH, calcium, and thyroid autoantibody [anti-thyroid peroxidase (anti-TPO)] levels were evaluated for all subjects (n = 214). Results: Lower serum 25OHD levels were present in groups I and II patients (12.6 ± 9.04 ng/mL, 10.6 ± 5.4 ng/mL respectively) than in group III subjects (22.8 ± 6.4 ng/m}L), (p < 0.00001). Although serum 25OHD levels inversely correlated with anti-TPO (r = –0.32, p = 0.0001) and parathormone (PTH) (r = –0.27, p = 0.0049) but no significant correlation of serum 25OHD levels was found with TSH (r = 0.04, p = 0.07) and FT4 levels (r = 0.02, p = 0.6). Hypothyroid patients (Group I) had higher anti-TPO levels than patient with GD and controls (groups II and III) (p < 0.0001). Conclusion: Our study demonstrated that lower vitamin D levels are found in AITD patients in at present. Severity and prevalence of vitamin D deficiency are higher in GD patients than hypothyroid patients. An inverse correlation was found in this study between antithyroid peroxidase antibodies (ATPO Ab) and vitamin D levels. We may propose that vitamin D deficiency is one of the potential factors in the pathogenesis of autoimmune thyroid disorders. Clinical significance: More larger studies, to evaluate the role of Vitamin D in pathogenesis of AITD and beneficial effect of its supplementation in treatment, are needed.