Objectives: The hypertensive disorders of pregnancy (HDP), especially severe preeclampsia are most common cause of neonatal and maternal mortality and morbidity. Alteration in metabolism of calcium and magnesium during pregnancy is considered to be one of etiological factor for pre-elampsia. Study Design: Case-control study. Settings: Departments of Pathology and Gynecology and Obstetrics, Bahawal Victoria Hospital. Period: September 2018 to June 2019. Material & Methods: To compare whether serum levels of calcium or magnesium showed significant change in mild and severe preeclamptic patients as compared to control group. Research population consisted of pregnant females that were divided into three groups. The mild and severe preeclamptic groups comprised of 55 and 26 participants respectively and 45 were included in control group. The serum calcium and magnesium levels were measured in these groups. Results: Maximum numbers of preeclamptic cases were presented at 28-32 week of gestation while severe pre-eclamptic group showed most cases in 33-36 weeks. In both groups, most of cases occurred in multiparous women as compared to nulliparous women. The normotensive group showed serum calcium and magnesium levels of 9.08±0.63 and2.12±0.22mg/dl while mild preeclamptic (mPE) had mean value of 7.91±0.64 and 1.58±0.42mg/dl and measurement were 7.67±0.48 and 1.26±0.44 in cases of severe pre eclampsia (sPE). Serum magnesium levels were significantly lower in sPE as compared to mPE (<0.0001) while difference was not statistically significant for serum calcium level (0.14). Conclusion: Both decrease level of serum calcium and magnesium might be risk factor in development of preeclampsia with more emphasis on role of low magnesium as a prognostic marker in severe preeclamptic cases.