Background Dengue virus infection can have different complications; the best known is hemorrhagic dengue fever. However, other effects such as neurological disorders may endanger the lives of patients. Dengue neurological manifestations can be confused with encephalitis symptoms and can lead to cerebral edema and death. Therefore, we consider important in the endemic areas to take into account the diagnosis of dengue encephalitis in patients with neurological disorders, and to request the determination of serology in cerebrospinal fluid for the NS1 antigen test. Case presentation We present the cases of two patients from the state of Morelos, Mexico, with 17 and 14 years of age. Both cases presented a rapid evolution characterized by fever, seizures and neurological deterioration secondary to severe cerebral edema that evolved to cerebral death in both cases. The diagnosis of brain death was confirmed by electroencephalogram in both patients. The two patients were submitted to serology for NS1 that tested positive in both cases. They died between the second and fifth day after admission. Conclusions Retrospective studies have found that up to 4% of the patients have dengue virus infections, which leads us to believe that in endemic areas, this infection should be suspected in cases of encephalic and febrile symptoms. RT-PCR should be performed to identify cases of encephalitis caused by the dengue virus, and early interventions should be performed to attempt to reduce the morbidity and mortality of these cases.(AU)