Purpose <p>Posterior rectus sheath hernia (PRSH) is a rare interparietal hernia that is often undetected or misdiagnosed on imaging. We conducted a retrospective review of a case series to define the specific imaging findings and clinical features associated with these hernias.</p> Methods <p>We retrospectively reviewed our institution’s imaging and surgical databases to identify patients with PRSH. Cases meeting strict diagnostic criteria of focal defect of the posterior rectus sheath with herniation into the rectus sheath and without features of a lateral (Spigelian) hernia—were included. Clinical presentation, imaging modality, hernia contents, and management were recorded.</p> Results <p>Seven patients with PRSH were identified (five spontaneous, two post-surgical). Presentations ranged from incidental, asymptomatic findings to abdominal pain and gastrointestinal obstruction symptoms. Contrast-enhanced CT was the primary imaging modality. Hernia contents included omentum, properitoneal fat and small bowel. While most patients did not require operative intervention, one patient had incarcerated small bowel through a ~ 1&#xa0;cm posterior sheath defect and required surgical repair.</p> Conclusion <p>PRSH is a rare interparietal hernia that often goes undetected. Radiologists should evaluate the posterior rectus sheath on CT and MRI for presence of PRSH. Careful description of the rectus sheath defect and its contents—particularly bowel—can guide appropriate management and distinguish cases needing surgical referral from those managed nonoperatively.</p>