In this paper, we demonstrate the effect of dielectric barrier discharge (DBD) plasma on lymphoma and normal blood mononuclear cells. Results indicates enhanced level of reactive oxygen species in U937 cells, which presented a compromised redox status evident from increased NADP þ /NADPH levels, reduced GSH/ GSSG ratios and decreases in the total endogenous antioxidant activity of cells. A plasma treatment drastically reduces cell viability, causing more severe damage to DNA and mitochondria, as determined by means of apoptosis indicators and related genes expression. Taken together, these findings indicate a significant level of apoptosis in plasma-treated lymphoma cells. This report lends insight into progress toward an appropriate therapy for blood cancers using non-thermal DBD plasma.