Glioblastoma is the most aggressive of all types of brain cancer. Especially in cancer research, the effectiveness of new drug candidates is being investigated with in vitro studies. In this study, we aimed to investigate the antineoplastic effects of curcumin administration at different doses on U251 cells. We hypothesize that curcumin inhibits U251 cell viability by modulating prooxidant-antioxidant mechanisms, triggering ROS production, apoptosis activity, and inflammation. In this study, IL-1β, TNF-α, caspase 3/9 levels, total antioxidant (TAS) and total oxidant levels (TOS) were measured. Cell viability was determined by MTT and 10, 20 and 40 µM curcumin doses were found to be effective doses. It was found that the administration of 40 µM curcumin induced oxidative stress, inflammation and apoptosis compared to the control group and other dose groups (p<0.05). No statistical difference was found in the 10 µM curcumin group. We found that 40 µM curcumin had a dose-dependent effect on proliferation and migration of U251 glioblastoma cells and significantly inhibited their proliferation.