Spontaneous retroperitoneal and rectus sheath hemorrhage (SRRSH) is associated with high mortality in the literature, but studies on the subject are lacking. The objective of this study was to identify early predictors of the need for angiographic or surgical intervention (ASI) in patients with SRRSH and define risk factors for mortality. We conducted a retrospective cohort study at a tertiary academic hospital. All patients with computed tomography-identified SRRSH between 2012 to 2017 were included. Exclusion criteria were age below 18years, possible mechanical cause of SRRSH, aortic aneurysm rupture or dissection, and traumatic or iatrogenic sources of SRRSH. The primary outcome was the incidence of ASI and/or mortality. Of 100 patients included (median age 70years, 52% males), 33% were transferred from another hospital, 82% patients were on therapeutic anticoagulation, and 90% had serious comorbidities. Overall mortality was 22%, but SRRSH-related mortality was only 6%. Sixteen patients underwent angiographic intervention (n = 10), surgical intervention (n = 5), or both (n = 1). Flank pain (OR 4.15, 95% CI 1.21-14.16, p = 0.023) and intravenous contrast extravasation (OR 3.89, 95% CI 1.23-12.27, p = 0.020) were independent predictors of ASI. Transfer from another hospital (OR 3.72, 95% CI 1.30-10.70, p = 0.015), age above 70years (OR 4.24, 95% CI 1.25-14.32, p = 0.020), and systolic blood pressure below 110mmHg at the time of diagnosis (OR 4.59, 95% CI 1.19-17.68, p = 0.027) were independent predictors of mortality. SRRSH is associated with high mortality but is typically not the direct cause. Most SRRSHs are self-limited and require no intervention. Pattern identification of ASI is hard.