BACKGROUND To evaluate tumor responses, event‐free survival (EFS), overall survival (OS), and toxicity of chemotherapy, children with neurofibromatosis type 1 (NF1) and progressive low‐grade glioma were enrolled into the Children's Oncology Group (COG) A9952 protocol and treated with carboplatin and vincristine (CV). METHODS Non‐NF1 patients were randomized to CV or thioguanine, procarbazine, 1‐(2‐chloroethyl)‐3‐cyclohexyl‐1‐nitrosourea, and vincristine in COG A9952. NF1 patients were assigned to CV only. NF1 patients and non‐NF1 patients who were treated with CV were compared with respect to baseline characteristics, toxicity, tumor responses, EFS, and OS. RESULTS A total of 127 eligible patients with NF1 were nonrandomly assigned to CV: 42 NF1 patients (33%) had events, and 6 (4.7%) died. The 5‐year EFS rate was 69% ± 4% for the CV‐NF1 group and 39% ± 4% for the CV–non‐NF1 group (P < .001). In a univariate analysis, NF1 children had a significantly higher tumor response rate and superior EFS and OS in comparison with CV‐treated children without NF1. NF1 patients and non‐NF1 patients differed significantly in amount of residual tumor, extent of resection, tumor location, and pathology. According to a multivariate analysis, NF1 was independently associated with better EFS (P < .001) but not with OS. NF1 patients also had a decreased risk of grade 3 or 4 toxicities in comparison with non‐NF1 patients. Three second malignant neoplasms occurred in NF1 patients receiving CV (CV‐NF1 group) at a median of 7.8 years (range, 7.3‐9.4 years) after enrollment, but there were none in the non‐NF1 group. CONCLUSIONS Children with NF1 tolerated CV well and had tumor response rates and EFS that were superior to those for children without NF1. Cancer 2016;122:1928–36. © 2016 American Cancer Society. Children with neurofibromatosis type 1 who are treated for low‐grade gliomas tolerate carboplatin and vincristine well and have tumor response rates and event‐free survival superior to those for children without neurofibromatosis type 1.