Diffuse low-grade gliomas (LGG) are rare tumors that affect young adult patients. The European Organization for Research and Treatment of Cancer (EORTC) and the Radiation Therapy Oncology Group (RTOG) have both developed their own clinical prognostic scores to assist clinicians in treatment decision-making. These criteria have been used to include patients in phase III studies. To date, it is unknown which is the best score to define the prognosis of LGG. Additionally, a pure clinical classification is probably not a sufficiently informative basis for choosing the proper treatment in different situations. A combined score with both clinical and molecular features will likely be indispensable.