Lateral abdominal wall hernias are defined as any defect lateral to the rectus sheath bounded by the costal margin cranially and the inguinal ligament caudally. The most common cause is prior surgery, with urologic procedures, retroperitoneal aortic exposures, renal transplants, and orthopedic bone harvest among the most common etiologies. In patients with a midline component of their hernia, or where mesh overlap beyond the linea alba to the contralateral side is required, lateral defects can be approached from a midline laparotomy (or robotically) in the supine position. This is done by completing a transversus abdominis release, gaining access to the retromuscular space inferiorly and superiorly to the defect, and connecting these planes laterally. Patients with isolated flank defects are approached from a lateral flank incision and using either retromuscular or preperitoneal dissection planes. This specific technique is described in this chapter along with special considerations around anatomy and mesh fixation.