Secondary tethering of the spinal cord in people with myelomeningocele (MMC) is almost universal but there is a relatively low incidence of the secondary tethered cord syndrome (S-TCS). In view of this, we wish to explore the notion that cord pulsation, as demonstrated by ultrasound of the spinal cord, can become an independent measure for increased tension of the spinal cord in patients with MMC. One-hundred and six patients with MMC underwent ultrasonographic examination of their back, a thorough physical examination, and a careful review of their clinical history. Of these patients, 53 had MRI of their back. Cord pulsation was graded and the statistical relation between pulsation and various clinical and MRI findings was analysed. Age and arm span were not correlated with grades of cord pulsation. The absence of cord pulsation correlated with the presence of symptoms but this relation may be explained by MRI findings of certain structural cord malformations and not by tethering per se. Assuming that cord pulsation is a reliable marker for the tension within the spinal cord, the results of our study suggest that overstretching of the cord is not the main cause for the development of the S-TCS.