The purpose of this study is to determine whether there is a relationship between the conus level and patients with a Chiari I malformation. This retrospective MRI study evaluated conus levels and degrees of tonsillar ectopia in 26 children ages 5-16 years with a Chiari I malformation. Our results show that there seems to be no relationship between the conus level and the amount of tonsillar ectopia that a child with a Chiari I malformation might have. In fact, there seemed to be an inverse relationship between these two entities. Interestingly, we have also found that of all coni located at the L2-L3 disc space or below, these patients had a syrinx associated with their Chiari I malformation and that all malformations without a syrinx had a 'normally' positioned conus medullaris. Copyright © 2001 S. Karger AG, Basel.