Aim. To investigate the effect of magnesium administered to the operative region muscle and administered systemically on postoperative analgesia consumption after lumbar disc surgery. Material and Method. The study included a total of 75 ASA I-II patients aged 18-65 years. The patients were randomly allocated into 1 of 3 groups of 25: the Intravenous (IV) Group, the Intramuscular (IM) Group, and the Control (C) Group. At the stage of suturing the surgical incision site, the IV Group received 50mg/kg MgSO4 intravenously in 150 mL saline within 30 mins. In the IM Group, 50mg/kg MgSO4 in 30 mL saline was injected intramuscularly into the paraspinal muscles. In Group C, 30 mL saline was injected intramuscularly into the paraspinal muscles. After operation patients in all 3 groups were given 100 mg tramadol and 10 mg metoclopramide and tramadol solution was started intravenously through a patient-controlled analgesia device. Hemodynamic changes, demographic data, duration of anesthesia and surgery, pain scores (NRS), the Ramsay sedation score (RSS), the amount of analgesia consumed, nausea-vomiting, and potential side effects were recorded. Results. No difference was observed between the groups. Nausea and vomiting side effects occurred at a rate of 36% in Group C, which was a significantly higher rate compared to the other groups (p < 0.05). Tramadol consumption in the IM Group was found to be significantly lower than in the other groups (p < 0.05). Conclusion. Magnesium applied to the operative region was found to be more effective on postoperative analgesia than systemically administered magnesium.