BACKGROUND Vitamin-D commonly known as Ergocalciferol (vitamin D2) & Cholecalciferol (vitamin D3) promotes the absorption and metabolism of calcium. Among children scarcity of vitamin D may cause rickets whereas osteomalacia both in adults and children having relevance with less circulating concentrations of 25OHD that is less than 20 nmol/L. OBJECTIVE To assess knowledge of undergraduate students about vitamin-D deficiency in various private sector universities of Karachi. STUDY DESIGN A cross-sectional study was conducted where structured questionnaire were distributed STUDY SETTINGS & PARTICIPANTS The targeted population was 100 subjects currently enrolled in medical universities. RESULTS According to the descriptive analysis, 100% students were aware of the importance of Vitamin D. However, only 38% of them knew that the deficiency of Vitamin D can cause tiredness, low mood, muscle and bone pain. 64% knew the beneficence of exposure of 10-15% of sunlight. CONCLUSION Students of private medical universities are aware of Vitamin D deficiency and its importance but its implementation is absent. Keywords Osteomalacia, Rickets, Vitamin D Deficiency, Osteoid, Trabecular Bone, Cholecalciferol, Ergocalciferol