Treatment of glioblastoma (GBM) is comprised of maximum safe surgical resection, radiotherapy and chemotherapy with Temozolomide. Nonetheless, the median survival of GBM patients is only 15 months with five-year survival rate of only 5.5%. Vorinostat, the clinically relevant histone deacetylase (HDAC) inhibitor, is a novel drug that inhibits cell proliferation and induces apoptosis in solid tumors. Following Vorinostat treatment, we show a significant decrease in hyperpolarized [1-13C] lactate-to-pyruvate ratio that was associated with enhanced survival of glioblastoma-bearing mice. This highlights the potential of hyperpolarized 13C MRSI for monitoring response to a type of anticancer therapy previously unexplored in GBM patients.