Mild encephalopathy/encephalitis with a reversible splenial(MERS) lesion is a clinic-radiological entity. The clinical features of MERS in neonates are still not systemically reported. This paper presents five cases of MERS, and the up-to-date reviews of previously reported cases were collected and analyzed in the literature. Here we describe five cases clinically diagnosed with MERS. All of them were neonates and the average age was about 4 days. They were admitted for the common neurological symptoms such as hyperspasmia, poor reactivity and delirium. Auxiliary examinations during hospitalization also exhibited features in common. In this report, we reached following conclusions. Firstly, magnetic resonance imaging revealed solitary or comprehensive lesions in the splenium of corpus callosum, some of them extending to almost the whole corpus callosum. The lesions showed low intensity signal on T1-weighted images, homogeneously hyperintense signal on T2-weighted images, fluid-attenuated inversion recovery and diffusion-weighted images, and exhibited an obvious reduced diffusion on apparent diffusion coefficient map. Moreover, the lesions in the magnetic resonance imaging disappeared very quickly even prior to the clinical recovery. Secondly, all the cases depicted here suffered electrolyte disturbances especially hyponatremia which could be easily corrected. Lastly, all of the cases recovered quickly over one week to one month and majority of them exhibited signs of infections and normal electroencephalography. Mild encephalopathy / encephalitis with a reversible splenial (MERS) lesion is a clinic-radiological entity. The clinical features of MERS in neonates are still not systemically reported. This paper presents five cases of MERS, and the up-to-date reviews of previously reported were were and analyzed in the literature. Here we describe five cases clinically diagnosed with MERS. All of them were neonates and the average age was about 4 days. They were admitted for the common neurological symptoms such as hyperspasmia, poor reactivity and delirium First, magnetic resonance imaging revealed solitary or comprehensive lesions in the splenium of corpus callosum, some of them extending to almost the whole corpus callosum. The lesions showed low intensity signal on T1-weighted images, homogeneously hyperintense signal on T2-weighted images, fluid-attenuat ed inversion recovery and diffusion-weighted images, and showed an obvious reduced diffusion on apparent diffusion coefficient map. Moreover, the lesions in the magnetic resonance imaging disappeared very quickly even prior to the clinical recovery. especially hyponatremia which could be easily corrected. Lastly, all of the cases had recently been over one week to one month and majority of them drawings signs of infections and normal electroencephalography.