Vitamin D (VD) and its relationship in systemic lupus erythematosus (SLE) is being studied, with many studies suggesting a relationship between VD deficiency and SLE onset/disease activity. This study investigated this in a region of India receiving low solar ultraviolet-B (UV-B) index (1). 109 SLE patients were enroled along with 109 healthy controls belonging to same ethnicity and localities. Demographic and clinico-laboratory information were recorded. VD status was assessed by estimating serum 25-hydroxyvitamin D (25-OH-D) concentrations (deficient: <20 ng/mL, insufficient: 21-29 ng/mL, and sufficient/normal: ≥30 ng/mL). The SLE Disease Activity Index (SLEDAI) scoring system was used to evaluate disease activity. The results showed that hypovitaminosis D was prevalent in 90.83% SLE patients [vs. 77.98% healthy controls. SLEDAI scores and 25-OH-D values were inversely associated. SLE patients with VD deficiency were more likely to have high/very high disease activity. Conversely, patients with high SLEDAI scores (>10) also had greater risks of being VD deficient. The authors conclude that VD deficiency is widespread in SLE. The relationship appears to be bidirectional, with VD status associated both as determinant and outcome of disease activity in SLE.