A pillow (1) for the treatment and/or prevention of cranial deformities in babies and infants, of the type comprising a depression to receive the head, the depression comprising a curved inclined portion located around an opening (2), which is closed off by a supporting portion (21) for the head of the baby or infant, located at an intermediate height in the pillow, in which the supporting portion comprises a deformable material and the inclined portion forms an angle (A) of more than 130° with the supporting portion in the area where the inclined portion and the supporting portion merge.