To date there have been no formal studies of the cost-effectiveness of magnetic resonance spectroscopy. Cost-effectiveness analysis was conducted by utilizing a decision-analytic model that compared MRS and standard of care to standard of care alone for recurrent glioma and necrosis differentiation. Our results showed that performing MRS was highly cost-effective with incremental cost-effectiveness ratios of -$98,978, -$50,666 and -$41,349 per quality-adjusted life-years over 5-year, 10-year and lifetime horizons. At the willingness-to-pay threshold of $50,000, performing MRS was more cost-effective with certainty of 96% to 97% over those time-horizons. MRS should be considered reimbursable by policy makers.