A cytotoxic lesion of the corpus callosum is a nonspecific secondary change in the corpus callosum that occurs as a result of various triggers and is detected using MRI. A clinical case of a cytotoxic lesion of the corpus callosum, detected using MRI of the brain with standard modes, is presented, which showed the characteristic changes in the corpus callosum in a patient with pneumonia. A follow-up MRI in 3.5 months, with complete recovery, showed no previously visualized changes in the corpus callosum, providing neuroimaging confirmation of the suspected lesion. MRI can be considered a highly informative method used to diagnose cytotoxic lesions of the corpus callosum, as well as a method of accurate topical diagnosis, allowing for clarification of the localization and extension of the lesion and differentiation from diseases that have similar MR signs.