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Objective: To summarize the clinical and prognostic features of children with opsoclonus-myoclonus-ataxia syndrome (OMAS). Methods: A total of 46 patients who met the diagnostic criteria of OMAS in the Department of Neurology, Beijing Children's Hospital from June 2015 to June 2023 were retrospectively analyzed. Centralized online consultations or telephone visits were conducted between June and August 2023. The data of the children during hospitalization and follow-up were collected, including clinical manifestations, assistant examination, treatment and prognosis. According to the presence or absence of tumor, the patients were divided into two groups. The chi-square test or Mann-Whitney U test was used to compare the differences between the two groups. Univariate Logistic regression was used to analyze the factors related to OMAS recurrence and prognosis. Results: There were 46 patients, with 25 males and the onset age of 1.5 (1.2, 2.4) years. Twenty-six (57%) patients were diagnosed with neuroblastoma during the course of the disease, and no patients were categorized into the high-risk group. A total of 36 patients (78%) were followed up for≥6 months, and all of them were treated with first-line therapy with glucocorticoids, gammaglobulin and (or) adrenocorticotrophic hormone. Among the 36 patients, 9 patients (25%) were treated with second-line therapy for ≥3 months, including rituximab or cyclophosphamide, and 17 patients (47%) received chemotherapy related to neuroblastoma. At the follow-up time of 4.2 (2.2, 5.5) years, 10 patients (28%) had relapsed of OMAS. The Mitchell and Pike OMS rating scale score at the final follow-up was 0.5 (0, 2.0). Seven patients (19%) were mildly cognitively behind their peers and 6 patients (17%) were severely behind. Only 1 patient had tumor recurrence during follow-up. The history of vaccination or infection before onset was more common in the non-tumor group than in the tumor group (55%(11/20) vs. 23%(6/26), χ² =4.95, P =0.026). Myoclonus occurred more frequently in the non-tumor group (40%(8/20) vs. 4%(1/26), χ² =7.23, P =0.007) as the onset symptom. Univariate Logistic regression analysis showed that the tumor group had less recurrence ( OR= 0.19 (0.04-0.93), P =0.041). The use of second-line therapy or chemotherapy within 6 months of the disease course had a better prognosis ( OR= 11.64 (1.27-106.72), P =0.030). Conclusions: OMAS in children mostly starts in early childhood, and about half are combined with neuroblastoma. Neuroblastoma in combination with OMAS usually has a low risk classification and good prognosis. When comparing patients with OMAS with and without tumors, the latter have a more common infection or vaccination triggers, and myoclonus, as the onset symptom, is more common. Early addition of second-line therapy is associated with better prognosis in OMAS.