Abstract: 　Objective　To investigate the brain magnetic resonance imaging (MRI) features and clinical manifestations of the patients with citrullinemia, and to promote awareness of, early diagnosis of and better treatment for the disease. Methods　One case with citrullinemia was reported, and other eight cases reported in the literature in nearly 14 years were reviewed. Results　The case was a 15-month-old girl with type I citrullinemia diagnosed by the mutation analysis of the ASS1 gene performed in local hospital after birth. The patient was admitted to our hospital for recurrent lethargy for a year and the high level of blood ammonia (311 μmol/L, normal range 9-33 μmol/L). The blood ammonia reduced to normal on the 11th day after arginine treatment. On MRI scans, the diffusion weighted imaging (DWI) showed diffuse hyperintensity on bilateral frontal, parietal and temporal cortex, which indicated restricted diffusion due to cytotoxic edema. On the follow-up MRI after 10 day’s treatment, the affected regions was similar but the intensity decreased compared to the previous scan,which accompanied by cerebral atrophy. Eight cases in the literature were reviewed, and the clinical manifestations in these patients were lack of specificity, the most common features included feeding difficulties, lethargy, and vomiting. Brain MRI was performed on 7 cases, computed tomography (CT) was performed on 1 case, with the result of cytotoxic edema in 3 cases and atrophy in 2 cases. Conclusions　 Citrullinemia often lacks of specific symptoms in the early phase. Brain MRI could provide the clinician a valuable help for early diagnosis and treatment of this disease.