Dynamic 13C data were acquired following injection of hyperpolarized [1-13C]pyruvate from 3 patients previously diagnosed with glioblastoma. Pyruvate, lactate and bicarbonate signal with high SNR were detected in human brain. Lactate/Pyruvate appeared to be relatively high in the contra-lateral, normal appearing brain. In contrast, tumor regions produced higher Lactate/Bicarbonate than contra-lateral brain. The contrast-enhancing lesion of one patient, who underwent surgical resection shortly after 13C imaging due to suspected recurrence, produced a relatively low level of Lactate/Pyruvate compared to contra-lateral brain and Lactate/Bicarbonate similar to the value in contra-lateral brain. Subsequent biopsy of the contrast-enhancing lesion indicated treatment effect.