Lumbosacral transitional vertebrae (LSTV) are a common finding in the general population. Their clinical significance is controversial with no consensus as to their relationship to low back pain or disc prolapse. However, on magnetic resonance imaging (MRI) they may be difficult to positively identify on sagittal sequences and can lead to confusion with respect to numbering of lumbar discs and vertebrae, with the consequent risk of surgical intervention at an inappropriate level. The imaging findings of LSTV on plain radiography and MRI are reviewed and their clinical significance discussed.