Leptomeningeal carcinomatosis is extremely rare in colorectal adenocarcinoma, its incidence is far less than 1%. The neurological symptoms are pleomorphic. The most common symptoms included Headache, ataxia, cranial nerve palsies, meningismus, focal weakness or numbness. MRI is the most sensitive and specific imaging method for screening, positive diagnosis and pre-treatment of leptomeningeal carcinomatosis. The presence of appropriate neuroimaging abnormalities in a patient with typical clinical features and history of colorectal adenocarcinoma enables to make the diagnosis of leptomeningeal metastases. As well as a biological confirmation is necessary. Treatment usually comprises site-specific radiation therapy in addition to intrathecal and systemic chemotherapy. The case aims to describe the MRI characteristics of leptomeningeal metastases so as to formulate the diagnosis and the subsequent treatment.