Vitamin D deficiency is becoming increasingly recognized as playing an important role in autoimmune diseases. The prevalence of vitamin D deficiency in systemic lupus erythematosus is likely to be due to many different factors, including renal disease, sunlight avoidance and disease activity itself. Beyond its role in bone metabolism, vitamin D is an important immunomodulatory agent and may have roles in the pathogenesis of the disease, in addition to the severity of lupus. Musculoskeletal pain, fatigue and depression are common in systemic lupus erythematosus, and vitamin D deficiency is implicated in these conditions. Cardiovascular disease is an important cause of premature mortality in systemic lupus erythematosus. Low-serum vitamin D is associated with increased cardiovascular disease and may provide a potential link between cardiovascular disease and lupus.