Chronic low back pain (CLPB) is one of the leading causes of physician office visits and work absenteeism in developed countries. Because many of the muscle groups involved in CLBP are easily accessible and respond well to injection, this disorder may be seen as particularly amenable to treatment with botulinum neurotoxin (BoNT). This chapter reviews the pathophysiology, diagnosis and treatment with BoNT of myofascial pain of muscles involved in lumbosciatic conditions (quadratus lumborum, iliopsoas and paravertebral). Physical examination of the patient is discussed and illustrated. Anatomy is reviewed, and anatomical diagrams are provided, along with discussion of guidance techniques, such as fluoroscopy, for the accurate placement and dosing of injections.