The relationship between the reduction rate of TAD or TPD by the cerebrospinal fluid in the patients and their clinical patterns has been studied. (1) No reduction of TAD and TPD occurred by the cerebrospinal fluid in the patients such as poliomyelitis, cerebral palsy or hydrocephalus. (2) However, it was demonstrated that TAD and TPD were reduced significantly by the cerebrospinal fluid in tuberculous meningitis and purulent meningitis, which revealed pleocytosis and high protein level of cerebrospinal fluid. (3) Reduction rate of TAD and TPD decreased as the clinical condition was improved.