We describe a patient with glioblastoma who showed very high levels of total protein and albumin in the cerebrospinal fluid. The patient was a 57-year-old man who underwent subtotal removal of a glioblastoma from the left temporal lobe. Two weeks after the operation, he had quadriplegia and a lumbar puncture was performed. The concentrations of total protein and albumin in the cerebrospinal fluid were 6000 mg/dl and 3600 mg/dl, respectively, which were more than 100 times higher than the upper limits of the reference ranges and were close to their serum levels. The magnetic resonance image suggested that these abnormal values were due to total spinal cord dissemination of the tumor. The results of the cerebrospinal fluid examination showed that the albumin concentration in the fluid might increase to the serum level and the prozone phenomenon should be kept in mind when measuring its concentration in the fluid.