1. Vitamin D deficiency has become a significant public health concern in India despite the country’s abundant sunlight. Studies suggest that a large proportion of the Indian population has inadequate Vitamin D levels due to limited sun exposure, indoor lifestyles, air pollution, and poor dietary intake. This deficiency affects people of all age groups and is increasingly encountered in routine clinical practice.Vitamin D plays a crucial role in maintaining calcium and phosphorus balance, promoting bone mineralization, supporting muscle function, and regulating immune responses. It is synthesized in the skin through exposure to ultraviolet B (UVB) rays and is obtained in small amounts from dietary sources such as fatty fish, egg yolks, fortified milk, and mushrooms.Clinical manifestations of Vitamin D deficiency vary depending on severity and duration. Common symptoms include generalized body aches, bone pain, muscle weakness, fatigue, and increased susceptibility to fractures. In children, severe deficiency may lead to rickets, while adults may develop osteomalacia and osteoporosis. Emerging evidence also suggests associations with diabetes mellitus, cardiovascular diseases, and certain autoimmune disorders.Diagnosis is primarily based on serum 25-hydroxyvitamin D [25(OH)D] levels. A level below 20 ng/mL is generally considered deficient. Additional investigations may include serum calcium, phosphorus, alkaline phosphatase, and parathyroid hormone levels.Management involves lifestyle modification, adequate sunlight exposure, dietary improvement, and supplementation. Cholecalciferol is commonly prescribed, with treatment tailored according to individual requirements and baseline Vitamin D status. Preventive measures such as food fortification, public awareness campaigns, and screening of high-risk groups are essential for reducing disease burden.