In 1936, Walter Mercer described a new method for the operative treatment of patients with spondylolisthesis. Using a transabdominal approach in two patients he inserted iliac crest bone graft into the intervertebral disc. His publication in the Edinburgh Medical Journal caused a furore as the levels operated on did not reflect the description and one of the two patients died post-operatively. However, Mercer continued to promote the operation in his textbooks. The anterior approach to the lumbar spine is now performed routinely. This paper explores Mercer's contribution to anterior spinal surgery.