Although surgery is generally accepted as an important initial treatment in patients with low-grade gliomas, the role of postoperative radiotherapy (RT) is the subject of ongoing controversy. What is the most appropriate timing of RT? Is it best to deliver RT immediately after surgery or to watch and wait until disease progression? Numerous retrospective studies have shown that immediate postoperative RT provides a survival benefit. A recently published prospective study conducted by the European Organisation for Research and Treatment of Cancer has also shown that immediate postoperative RT significantly improved 5-year progression-free survival, but overall survival was not improved. Given the uncertainty about the overall survival benefit of immediate RT and the potential for radiation-induced toxicity, it is important to consider prognostic factors when selecting patients. Subgroups of patients with poor prognostic factors are more likely to benefit from immediate postoperative RT. Available data indicate that a carefully balanced therapeutic approach is needed to optimize treatment outcomes in patients with low-grade gliomas. Patients with more aggressive disease and a high risk of malignant transformation will likely benefit from immediate RT, whereas patients with low-risk disease, particularly oligodendrogliomas, can reasonably be observed. However, one cannot exclude the possibility that delaying RT may result in a worse long-term clinical outcome.