Background: Tuberculosis, a public health emergency, has continued to be burden for society both in terms of mortality and morbidity. Once diagnosed, the follow up for assessment is usually done clinically or methods which are not very effective or require expertise. Objective: To estimate Serum Magnesium levels in Pulmonary Tuberculosis. METHODS: This prospective study was conducted from inpatient and outpatient attached to Bapuji Hospital and Chigateri General Hospital attached to J.J.M. Medical College, Davangere attending the RNTCP clinics and inpatients. In the present study, 50 patients and 50 controls were included after fulfilling the inclusion and exclusion criteria. Appropriate investigations were done and patients were followed up for 2 months. Serum Magnesium levels were estimated at the start of treatment and 2months after the treatment. RESULTS: The mean age in study group was 39 ± 14.4 years with male predominance. ESR was elevated in all patients and significant biochemical abnormality detected was raised globulin levels. The Mean serum magnesium levels pre-treatment was 1.76 ± 0.24 mg/dL and post treatment were 2.00 ± 0.13 mg/dL. Magnesium levels were lower with more severe disease and with prolonged duration of illness.