Mild encephalitis/encephalopathy with a reversible lesion in the splenium (MERS) is a clinico-radiological syndrome with mild central nervous system symptoms and a reversible lesion in the splenium of the corpus callosum. It is mainly associated with a number of viral and bacterial infections, including Coronavirus disease 2019 (COVID-19). In this paper, we report four MERS patients. One had a mumps infection, the second had aseptic meningitis, the third had Marchiafava-Bignami disease, and the fourth had atypical pneumonia associated with COVID-19 infection. [ABSTRACT FROM AUTHOR]