Gliomas are the most common primary intracranial tumors, representing at least 75% of all primary malignant brain tumors. Histopathologically, gliomas are classified into different subgroups including astrocytomas (60-70%), oligodendrogliomas (10-30%), ependymomas (\<10%) and mixed gliomas (i.e. oligoastrocytomas) depending on the cell type from which they originate. The World Health Organization currently classifies gliomas based on histopathological analysis in which the presence (or absence) and the degree of specific histopathological features determines the grade of malignancy. Grade I (pilocytic astrocytoma) and grade II (diffuse astrocytoma, oligodendroglioma, mixed oligoastrocytoma, and pleomorphic xanthoastrocytoma) are termed low-grade gliomas (LGGs), whereas grade III (anaplastic astrocytoma, anaplastic oligodendroglioma or anaplastic oligoastrocytoma) and grade IV (glioblastoma) represent high-grade gliomas (HGGs). Given the incurable nature of gliomas, the maintenance or improvement of the patient's quality of life are extremely important. The benefits of multimodal treatment strategies, in terms of prolonged survival or delay of progression, have to be carefully balanced against the side effects of the treatment, which may adversely influence patient's functioning and well-being during his/her remaining life span. Measuring a brain tumor patients functioning and well-being goes far beyond assessing (progression-free) survival or tumor response to treatment on imaging. A more integrated way to measure patients functioning and well-being is the assessment of a patient's health-related quality of life (HRQOL). HRQOL is defined as a personal self-assessed ability to function in the physical, psychological, emotional, and social domains of day-to-day life. The main goal of this study is to perform a large-scale, prospective and long-term analysis of the HRQOL in patients diagnosed with glioma.