Pain after lumbar spine fusion surgery is often difficult to control in the immediate postoperative period. Historically, opioids have been the mainstay of treatment, but are associated with many unwanted side effects as well as increased hospital length of stay. The ultrasound-guided erector spinae plane block (ESP) is a relatively safe and simple regional option for the management of acute postoperative pain after spine surgery without the technical difficulty or complications noted with paravertebral injection (eg, pneumothorax, hematoma). To date, there have been reports of preoperative placement of ESP block prior to spine surgery with some success. We present a report of two cases that highlight the efficacy of the ESP block as an early postoperative "rescue" regional anesthetic technique in lumbar spine surgery. These cases demonstrate the potential effectiveness of a "rescue" use of the ESP block in patients having uncontrolled or poorly controlled pain in the early postoperative period with no evidence of significant side effects.