From the results of ICP determination in 6 cases of macrocrania, it is evident that Lundberg's pressure wave (plateau wave, B wave) can be sufficiently adapted for evaluating abnormality under the semi-closed circumference like infants. ICP determination in the case of macrocrania with mild enlarged ventricles important for knowing pathologic changes. In particular, pressure variation and amplitude changes during REM period seem to be an interesting index for knowing the involvement of venous function. The increased ICP during REM period was also observed in a patient with holoprosencephaly having brain stem formation only, suggesting an important relationship between brain stem and increased ICP during REM period.