A glioblastoma multiforme xenograft was established in athymic nude mice via inoculation of glioblastoma cells that stably express luciferase (U87MG-LucNeo), and was monitored weekly using bioluminescence imaging (BLI). In the control groups, a steep rise in the signal was associated with the death of mice. As an adjuvant therapy, cetuximab (0.5 mg, two times) was intraperitoneally administered 4 weeks after nitrosourea treatment. For a salvage therapy, cetuximab (0.5 mg, two times) was intraperitoneally administered when recovery of the bioluminescence signal was detected after nitrosourea monotherapy. The antitumor effects of cetuximab adjuvant therapy were superior to those of nitrosourea monotherapy and cetuximab salvage therapy. This finding was consistent with the results from a survival comparison among nitrosourea monotherapy, adjuvant and salvage therapy with cetuximab. These results suggest that BLI could be used as a simple tool for predicting the efficacy of various anticancer treatments in mouse models of brain tumors. The administration of cetuximab as an adjuvant to the conventional chemotherapeutic agent is more efficient than salvage therapy.