OBJECTIVES: To characterize the usage of Temozolomide (TMZ) in a real-world setting among patients with glioblastoma. METHODS: Adult patients diagnosed with malignant brain cancer (ICD9-CM, 191.XX), who underwent brain-related surgery 90 days prior to the first TMZ dose and had ≥ 24 months of continuous enrollment, were identified in the IMS Pharmetrics Lifelink Plus claims database. The TMZ + radiation subgroup was used to reflect glioblastoma patients and differentiate them from patients with lower-grade gliomas. Descriptive statistics were generated for patient demographics, insurance-related variables, co-diagnoses, concomitant medications, chemotherapy cycle-duration, and TMZ dose. The index date was defined as the first claim for TMZ, and certain variables were assessed for pre- and post-12 month periods. Statistical comparisons between pre- and post-index were performed using McNemar’s tests. RESULTS: A total of 1,126 patients met the inclusion criteria and the mean age was 52.7 yrs. (SD=10.9). There was a significant increase in the use of concomitant medications (antianxiety, antidepressants, and antiemetic) as well as co-diagnoses (depression, fatigue, seizure/epilepsy, and hearing loss) in the post-index period (p<0.001). However, in this same period, corticosteroid and pain medication use significantly decreased as did the co-diagnoses of aphasia and headache (p<0.001). TMZ mean starting dose, duration, and number of maintenance phase cycles was 154.4 mg (SD=77.9), 46 days (SD=12), and 7 cycles (SD=3), respectively. Following the first dose, 73% of patients experienced a TMZ dose increase. CONCLUSIONS: Post-index, patients experienced a complex change in both concomitant medications and co-diagnoses, possibly reflecting both a decrease in tumor mass and side effects of the TMZ + radiation therapy. These initial findings warrant further investigation of TMZ as real-world standard-of-care in glioblastoma.