Background: hypertension is one of the leading cause of morbidity and mortality and must me studied rigorously. One of the factors influencing blood pressure is magnesium level and hence research on the same is very important. A case control study, aiming to understand the correlation of serum magnesium with Blood pressure among normotensives and hypertensive patients. Materials and Methods: The study in Vijayapura in Karnataka had a total of 156 participants divided in two groups of 78 each. Group A with 78 cases with normal blood pressure as control and group B with 78 cases of primary hypertension. Individuals with who were known cases of secondary hypertension like chronic kidney disease were not included. The patients who were included gave their consent. In order to evaluate further proper procedure was followed to take patients blood pressure and blood sample. For normally distributed continuous variables between three groups will be compared using t- test For not normally distributed variables Kruscal walli’s test will be used. Categorical variables between two groups will be compared using Chi square test. Results: Out of a total 78 cases in the normotensive group 11 have a sr magnesium level of 1.8 while the remaining 67 patients have a level of 1.8 or higher. Normotensive group has only 14% of patients with hypomagnesemia. Out of a total 78 cases in the normotensive group, 54 have a sr magnesium level of less than 1.8 while the remaining 24 patients have a level of 1.8 or higher. Hypertensive group has 69% of patients with hypomagnesemia. Which is 55% higher than the normotensive group.When the 2 groups are compared using t-test for equality of means it is found that the p-value for sodium is slightly below < 0.05 which is significant. It also showed Mg with a p-value of 0.004 which is well below 0.05 which is statistically significant.With a p value of 0.09 for systolic blood pressure and a value of 0.20 for diastolic blood pressure. There is no corelation between sr mg and SBP/DBP within the hypertensive group itself. Conclusion: From the study conducted, the following observations were madePatients in the hypertensive group have 5 times more cases of low serum magnesium. Primary hypertension has significant negative corelation to serum magnesium levels.