Standard therapeutic options for brain tumors include surgery, radiotherapy, and chemotherapy. Unfortunately, these same therapies pose risks of neurotoxicity, the most common long-term complications being radiation necrosis, chemotherapy-associated leukoencephalopathy, and cognitive deficits. Currently, there is no consensus on the treatment strategy for these tumors. Because of the relatively slow growth rate of low-grade gliomas, patients have a relatively long expected survival. Compared to traditional outcome measures like (progression-free) survival, evaluation of health-related quality of life may be time-consuming and burdensome for both the patient and the doctor. Besides, given the relatively low incidence of brain tumors and the ultimately fatal outcome of the disease, the interest in HRQOL emerged relatively late in these patients. Moreover, the notion that the disease itself may affect the patient's ability to judge his or her own functioning may hinder the use of patient self-reported measures. The studies presented in this chapter describe outcomes of both single dimensional and multidimensional methods of studying HRQOL. Although only few studies incorporated HRQOL as outcome measure, most studies have embraced the notion that an accurate assessment of HRQOL must be based on patient self-report. HRQOL instruments from other cancer groups are adapted for use with brain tumor patients. The multidimensional scales used to study changes in HRQOL studies in brain tumor patients provide a more comprehensive view of what is important to the patient concerning living with their disease and receiving treatment. In future trials, more sensitive measures of long-term cognitive, functional, and HRQOL outcomes on LGG patients at important time points over the disease trajectory are needed to better understand the changing needs that take place over time.