The sheep model is frequently used for pre-clinical trials of spinal implants and vertebral interbody fusion devices. The lack of a well-documented multisegmental approach to the ventral aspect of the lumbar vertebrae has limited these trials to a posterior approach to the spine. A retroperitoneal approach to the sheep lumbar vertebrae was established and tested. One hundred and five sheep underwent the surgery. No major complications are reported. Major anatomical differences between sheep and humans were observed and documented. Anatomical variations in the sheep segmental vessel anatomy were also observed. Comprehensive knowledge of the retroperitoneal approach in sheep will facilitate pre-clinical studies testing ventral spinal implants or fusion techniques.