Abstract: The aim of this study was to detect antibodies to vitamin D in systemic lupus erythematosus (SLE) and other autoimmune diseases. The results may shed light to a novel aspect of vitamin D deficiency in autoimmune diseases. Sera from 171 patients with SLE, 56 with antiphospholipid syndrome (APS), and 18 with pemphigus vulgaris (PV) were studied employing an enzyme-linked immunosorbent assay for anti-vitamin D antibodies along with 94 healthy blood donors. In parallel, vitamin D concentrations in the serum were determined by a DiaSorin commercial kit (LIAISON 25 OH vitamin D). Antibody-positive and antibody-negative individuals were compared with respect to demographic variables, SLE disease activity index (SLEDAI) score, autoantibodies profile, and serum vitamin D levels. Anti-vitamin D antibodies were detected in 7 (4%) of 171 patients with SLE, in 2 (3.5%) of 56 of sera from patients with APS, and in 2 (11%) of 18 sera from patients with PV. Vitamin D levels were similar in both SLE groups with and without anti-vitamin D antibodies. Demographic features, organ involvement, SLEDAI score, and autoantibodies did not differ between the groups. Except for anti-dsDNA antibodies, in which anti-vitamin D antibodies were strongly associated with these antibodies in sera from SLE patients (P= 0.0004). Anti-vitamin D antibodies are observed in a subset of patients with SLE, APS, and PV, and are associated with anti-dsDNA antibodies in SLE. Further studies are required to explore the potential diagnostic and prognostic role of these novel antibodies in SLE.