Back pain strikes four of five people at some time in their lifetime, with the annual costs for treatment reaching tens of billions of dollars (Ekman et al., Spine 30:1777–1785, 2005). Most back pain is related to muscle strain and resolves over 2–5 days. Unfortunately, 5% of the population with back pain will have pain that continues for more than 3 months, significantly altering their lifestyle, occupational productivity, and activities of daily living. The complications, uncertain outcomes, and permanency of spine surgeries have altered the management algorithm physicians follow when treating back pain (Juratli, Spine 31:2715–2723, 2006; Van Tulder et al., Eur Spine J 15(Suppl 1):S83–S92, 2006). Present trends favor trying conservative therapies until they are exhausted, with the hope of delaying or avoiding spine surgery (Amundsen et al., Spine 25:1424–1436, 2000; Carey et al., N Engl J Med 333:913–917, 1995; Carrino et al., Radiology 225:723–729, 2002). The noninvasive and minimally invasive treatments currently available include rest, ice packs, heating pads, physical therapy, nonsteroidal anti-inflammatory medications, muscle relaxants, Botox injections, chiropractic manipulations, osteopathy, massage, acupuncture, yoga, physical therapy, psychological therapies, and weight reduction (Van Tulder et al., Eur Spine J 15(Suppl 1):S83–S92, 2006). Gaining in popularity are fluoroscopic-guided back pain injections using corticosteroids and anesthetics (Bartynski, Am J Neuroradiol 26:502–505, 2005; Johnson, Am J Neuroradiol 20:697–705, 1999). Nerve ablation techniques, including heat (rhizolysis) and cold (cryoneurolysis), are used when more straightforward injections are ineffective. Neural stimulators, if practical, may be implanted. The strengths of using injections to treat back pain lie in their ability to effectively target disease in a minimally invasive manner with a reasonably good outcome and few complications. Unfortunately, there are few well-controlled studies with variable outcomes published in the literature (Van Tulder et al., Eur Spine J 15(Suppl 1):S83–S92, 2006). Long-term outcomes are not as good for specific populations, and which patients fall into these groups is not well understood. Studies examining which patients with back pain are likely to respond to specific types of injections have not been conducted. The incidence of devastating complications is not entirely known and was primarily anecdotal until the past decade (Kennedy, Pain Med 10:1389–1394, 2009). The incidence of minor complications is also unclear. Emerging evidence suggests that short-term pain relief, up to 3 weeks, is generally possible. Long-term relief is less predictable, especially in patients with chronic back pain (Abdi, Pain Physician 8:127–143, 2005; Arden, Rheumatology (Oxford) 44:1399–1406, 2005). Determining which patients will respond to a therapeutic injection is difficult, but machine learning methods may be able to use a broad range of data to predict favorable outcomes in an individual. Trial injections are often used to help distinguish those who will respond from those who will not. The focus of this entry is on the various types of injections that can be performed in the lumbar spine. Most injections should be performed with the aid of image guidance. Currently, the most popular method is fluoroscopy, but CT, ultrasonography, MRI, and image fusion guidance are also used. Needle guidance using sensors within the needle is employed with 3D datasets from CT or MRI fused with active ultrasound imaging. The software predicts the needle path, and this can be adjusted to avoid vessels and bony prominences. Techniques, potential complications, and pertinent literature are discussed with each topic.