BACKGROUND: Literature remains scant regarding the subset termed 'massive hiatal hernias'. This case report delineates the surgical management and subsequent outcomes of two squirrel monkeys diagnosed with massive hiatal hernias. OBJECTIVES: This case report delineates the surgical management and subsequent outcomes of two squirrel monkeys diagnosed with massive hiatal hernias, offering insights into the feasibility and criticality of timely interventions, underscored by postoperative care and dietary management. METHODS: The radiographic diagnosis is suggestive of a massive hiatal hernia, and this clinical suspicion was definitively corroborated during the subsequent surgical intervention. Left gastric fixation was used to reposition the herniated organs and repair and reinforce the hiatus. RESULTS: One subject died of unforeseeable complications 3 days after post-discharge. The other subject's hospitalization was extended to 40 days to ensure optimal recovery. Upon being discharged, the monkey's condition remained stable. CONCLUSIONS: This case suggested achieving long-term postoperative survival of a massive oesophageal hiatal hernia. Surgical management hinges not merely on the surgery but on rigorous postoperative care coupled with stringent dietary regulation.