Non thermal atmospheric plasma is a new promising candidate in anticancer therapy. We have already reported the absence of skin damage induced by our plasma treatment. Preliminary results suggested that this treatment could also induce an antitumor effect on U87 malignant glioma xenografts, and we conducted this work to evaluate the antitumor efficacy of plasma in this model. Antitumor effects were assessed by tumor volume measurement and bioluminescence imaging (BLI). Plasma treatment was applied during five consecutive days in open air with a μs-duration pulsed floating electrode dielectric barrier discharge (FE-DBD), which delivered about 0.75 W at 200 Hz on the mouse skin. Our results showed a significant tumor volume decrease of 56% for treated mice at the end of the treatment, with a concomitant decrease of BLI intensity. Moreover, this tumor volume reduction translated into an increase of mouse life span of 60%, median survival being 9.5 and 15.0 days for control and plasma-treated mice, respectively. In conclusion, our study demonstrates a marked antitumor effect of plasma treatment in U87 glioma xenografts. These results, obtained in both a radio and chemoresistant model, are very promising and highlight the potential of plasma treatment as an anticancer treatment with little or no toxic side effects.