This study presented results of 52 patients with IDH-mutant diffuse gliomas treated with proton radiation. Tumor classified by WHO grade 2, 3 and 4 were 22, 25 and 5 cases. The median follow-up time was 21.7 months. The 12/24-month PFS and OS rates for the entire cohort were 97.6%/78.4% and 100%/91.0%. No severe acute toxicity (grade 3 or above) was found. Late grade 3 radio-necrosis was developed in one case of oligodendroglioma, WHO grade 3.