Objective: To explore the clinical features of first-onset myelin oligodendrocyte glycoprotein-IgG-associated disorders. Methods: We undertook a retrospective analysis of the first attack in 56 MOGAD patients. Numerous clinical parameters were evaluated, including age, gender, symptoms, MRI, fundus, CSF, MOG-IgG titer level, EDSS score, and the interval between the first and second attack. Results: The study cohort included 56 patients: 36 males and 20 females (male: female ratio = 1.8:1), with a median age of 23 years (range, 10-58 years). The first-onset manifestations were meningoencephalitis (32.14%), optic neuritis (25.00%), myelitis (17.86%), brainstem encephalitis (14.28%), and multiple symptoms (10.71%). The brain MRI lesions have the characteristics of large volume and scattered distribution. Brain stem involvement is usually accompanied by hemispheric lesions. Short segmental damage is common in patients with spinal cord involvement. About half of the patients had mild to moderate elevations of leukocytes and proteins in the cerebrospinal fluid. In patients with optic neuritis, significant papilledema can be seen in the fundus. The titer of MOG-IgG antibody was mostly weak positive. The EDSS score was 0.50–8.50, with an average of 3.55±0.25. The titers of MOG-IgG antibody at first onset were mostly weakly positive, MOG-IgG titer does not reflect disease severity or recurrence risk (p>0.05). After the first onset, most of the patients (54/56, 96.43%) recovered well without sequelae. A small number of patients (2/56, or 3.57%) had sequelae. 75.00% of patients experienced disease recurrence. The second recurrence lasted from 1 month to 60 months, with an average of 6 (21) months. The recurrence risk of patients without immunomodulatory therapy was significantly higher than that of patients with immunomodulatory therapy. There was no significant correlation between the symptoms of the second relapse and those of the first. Conclusion: The age of the first onset of MOGAD is mostly in teenagers and young adults, 75.00% before the age of 40. There is no incidence of MOGAD in the elderly. It affects slightly more men than women. Clinical manifestations are varied. The vast majority of patients have a good prognosis after the first onset. Most patients do not relapse after immunomodulatory therapy.