The accuracy and reliability of a non-invasive method for the measurement of intracranial pressure through the fontanelle without puncture was tested during 12 or even 24 h recordings. Wealthall and Smallwood modified aplanation transducer was first used. A metal frame was developed to secure the transducer rigidly over the fontanelle so that the recording could take place with the infant in any position and completely free of its movements. Simultaneous recordings of extradural or intraventricular pressure showed that the measurements were accurate to about 1 or 2 cm H2O in a neurosurgical environment (i.e., large fontanelles with pressure over 10 cm H2O). For smaller fontanelles or low or even negative intracranial pressure, a smaller transducer seems to be needed. The preliminary test of a plane strain gauge transducer that partially fills this need is shown.