To evaluate the surgical effect on survival in patients with incidental low-grade glioma (LGG) through comparison between asymptomatic and symptomatic patients. The medical records of surgically treated adult cerebral incidental LGG (iLGG) patients in our department between January 2008 and December 2015 were retrospectively reviewed. The survival of patients was calculated starting from the initial imaging diagnosis. Factors related to progression-free survival (PFS), overall survival (OS) and malignant progression-free survival (MPFS) were statistically analyzed. Seventy-five iLGG patients underwent surgery: 49 in the asymptomatic group, who underwent surgery in the asymptomatic period, and 26 in the symptomatic group, who underwent surgery after the tumor had grown and the patients had developed tumor-related symptoms. Significantly more tumors were initially located adjacent to the functional area in the symptomatic group than in the asymptomatic group (P<0.05), but there was no significant difference in the total resection rate between the two groups. The incidence of postoperative complications (15.4%) and postoperative epilepsy (23.1%) was higher in the symptomatic group than in the asymptomatic group (4.1% and 10.2%, respectively). Multivariate analysis showed that surgical timing, namely, surgery performed before or after symptom occurrence, had no significant effect on PFS, OS or MPFS, while total resection significantly prolonged PFS, OS and MPFS, and the pathology of oligodendroglioma was positively correlated with PFS and OS (P<0.05). Surgical timing for iLGGs should facilitate total resection. If total resection can be achieved, even after symptom occurrence, patients can achieve comparable survival benefits to those treated with surgery in the asymptomatic phase.