BACKGROUND: N-methyl-d-aspartate receptor (NMDAR) antibody encephalitis appears common in the world, but the number of clinical cases in Vietnam which were recorded is rare. CASE REPORT: We describe two new cases of disease in recent years with the aim of contributing to diagnosis and treatment experiences. These cases were noted over the past 3 years with the patients who have been treated at lower levels but have no results. They came to us when symptoms became worse and therefore required prolonged treatment with special intensive care facilities. The atypical and easily confused symptoms are the reasons that make the disease be detected late; leading to a much higher cost of treatment and the complication may appear in the patient. In the past, patients with these manifestations were diagnosed with unexplained encephalitis and severe sequelae or death. Autoimmune encephalitis has many types; NMDA encephalitis associated with ovarian teratoma is the most common autoimmune encephalitis in young women. CONCLUSION: In conclusion, based on the case report, we hope to contribute some experiences on the diagnosis and the strategy in early treatment. With most female patients at very young age, early treatment to avoid complications will help patients have a quality life and maintain reproductive function.