This study examines trends and regional variations in lumbar spine surgery rates in the United States from 1992 to 2003 using national Medicare data. The primary objectives were to describe recent trends and geographic variations in population-based rates of lumbar fusion, laminectomy, and discectomy. The results show a steady increase in lumbar fusion rates from 0.3 per 1,000 enrollees in 1992 to 1.1 per 1,000 enrollees in 2003. Regional rates of lumbar discectomy and laminectomy showed a nearly 8-fold variation between 2002 and 2003, while lumbar fusion rates showed a nearly 20-fold range, representing the largest coefficient of variation among any surgical procedure. Medicare spending for inpatient back surgery more than doubled over the decade, with lumbar fusion spending increasing by over 500%, from $75 million to $482 million. The rate of specific procedures within a region remained stable over time, but there was a marked increase in fusion rates and costs. Rates of back surgery were not correlated with the per-capita supply of orthopedic and neurosurgeons. The study highlights the need for more scientific evidence and research to improve the basis for clinical practice and reduce variability in surgical decision-making.This study examines trends and regional variations in lumbar spine surgery rates in the United States from 1992 to 2003 using national Medicare data. The primary objectives were to describe recent trends and geographic variations in population-based rates of lumbar fusion, laminectomy, and discectomy. The results show a steady increase in lumbar fusion rates from 0.3 per 1,000 enrollees in 1992 to 1.1 per 1,000 enrollees in 2003. Regional rates of lumbar discectomy and laminectomy showed a nearly 8-fold variation between 2002 and 2003, while lumbar fusion rates showed a nearly 20-fold range, representing the largest coefficient of variation among any surgical procedure. Medicare spending for inpatient back surgery more than doubled over the decade, with lumbar fusion spending increasing by over 500%, from $75 million to $482 million. The rate of specific procedures within a region remained stable over time, but there was a marked increase in fusion rates and costs. Rates of back surgery were not correlated with the per-capita supply of orthopedic and neurosurgeons. The study highlights the need for more scientific evidence and research to improve the basis for clinical practice and reduce variability in surgical decision-making.