"Benign convulsions with mild gastroenteritis (CwG)" is recognized as a benign situation-related seizure. Neuroimaging studies usually do not reveal any abnormalities. We report MRI diffusion-weighted image (DWI) findings of two patients who were clinically diagnosed with CwG. DWI demonstrated a transient abnormality in the splenium of the corpus callosum. Although viral encephalitis or encephalopathy should be carefully differentiated in patients clinically diagnosed with CwG, frequent seizures might cause transient splenial abnormality in patients with CwG.