We wanted to verify the magnetic resonance imaging (MRI) abnormalities that occur in the central nervous system (CNS) of cobalamin-deficient (Cbl-D) rats. The rats were made Cbl-D by means of total gastrectomy or feeding a Cbl-D diet. MR images of the cervical tract of the vertebral canal were recorded using a vertical spectrometer, and the volume of cerebrospinal fluid (CSF) in this part of the vertebral canal was calculated. The findings of the present study demonstrate that: (i) there was a significant decrease in cervical tract CSF volume regardless of the way in which the vitamin deficiency was induced; (ii) this volume normalized in the totally gastrectomized rats after chronic Cbl treatment; (iii) no blood-brain or blood-CSF barrier lesions were found in Cbl-D rats, using either MRI with a paramagnetic contrast agent or calculating the albumin CSF/serum concentration quotient. Cbl deficiency decreases CSF volume in the cervical tract of the vertebral canal of the rat, without apparently impairing the blood-brain barrier.