Spinal dysraphism is relatively common in children and includes a wide spectrum of congenital anomalies in the normal closure of the posterior elements of the spine. The prognosis will depend mostly on early diagnosis and treatment. Occult spinal dysraphism may present without external anomalies and the diagnosis could be suspected lately, when neurological symptoms are present and often irreversible. Occult spinal dysraphism is frequently associated to a tethered cord, most commonly secondary to the presence of a lipoma. Ultrasonography has been proven highly sensitive in the detection of intraspinal anomalies, especially in the diagnosis of tethered cord, in children under two years of age due to lack of ossification of the posterior elements of the spine. Today ultrasonography should be the examination of choice in all those patients in whom some kind of spinal dysraphism is suspected. We report our experience with three infants with occult spinal dysraphism in whom diagnosis was initially made by US and later on proved by either computed tomography, magnetic resonance or myelography. All of them had corrective surgery and neurological abnormalities were not detected afterwards.