Background: Vitamin D insuffi ciency has been associated with several adverse health outcomes, including pregnancy outcomes, and is increasingly recognised as a public health concern. It is responsible for approximately 50,000 maternal deaths yearly worldwide, 25% of all cases of fetal growth restriction, and 15% of preterm births in developed countries. Objective: Vitamin D and magnesium sulfate act by altering the calcium levels so this study was conducted to see if vitamin D supplementation has any additive role to magnesium sulfate treatment in preeclampsia and in preventing its progression to eclampsia. Materials and Methods: This cross sectional study was conducted in the Department of Biochemistry, in collaboration with Department of Obstetrics and Gynecology, at MMIMSR, Mullana (Ambala), Haryana, India. One hundred and fifty pregnant females attending the Obstetrics clinic were selected for the study and were divided into three groups of fi fty each. Group I (Control): Normotensive healthy pregnant females, Group II: Preeclamptic patients receiving magnesium sulfate therapy and Group III: Preeclamptic patients receiving magnesium sulfate therapy along with vitamin D supplementation (33000 IU once every two weeks, orally after 28 weeks up to 36 weeks). The samples were analysed for serum total calcium, ionized calcium, serum phosphorous, serum magnesium, serum albumin, serum alkaline phosphatase, serum creatinine and serum uric acid. Results: Mean levels of total calcium, ionised calcium, phosphorous, magnesium, albumin, alkaline phosphatase, creatinine and uric acid before and after delivery were calculated in all the three groups. Serum calcium (total and ionised), albumin and magnesium were decreased in preeclamptic women whereas serum phosphorous and uric acid were increased in preeclamptic. Vitamin D supplementation improved calcium status, uric acid level and albumin level were also improved. Conclusion: Vitamin D supplementation in early pregnancy improves the calcium status and reduces the severity of preeclampsia.