Rationale: Despite clinical-proven benefits of immune checkpoint inhibitors (ICIs) on advanced lung cancer, rare but life-threatening immune-related adverse events (irAEs) have been reported. Pancreatitis is a rare irAE that can occur with any ICI. Patient concerns: A 53-year-old man with locally advanced non–small cell lung carcinoma was treated with radiochemotherapy and then durvalumab (anti–programmed cell death ligand 1 therapy). Twelve weeks after the beginning of ICI, he reported abdominal pain and anorexia. Blood test showed high level of lipase. Abdominal computed tomography revealed a swollen pancreas. These findings were confirmed by magnetic resonance cholangiopancreatography and biliopancreatic endoscopic ultrasonography. Diagnoses: Grade IV immune-related pancreatitis. Interventions: The patient was treated with corticosteroid therapy, resulting in clinical, radiological, and biological improvement. Outcomes: During the first month, corticosteroid therapy could not be decreased under 1 mg/kg/d because of symptoms recurrence and lipasemia rerising. Four months after this episode, the patient died from acute ischemia of the lower limbs while he was on <20 mg/d of corticosteroid. Lessons: To the best of our knowledge, immune-related pancreatitis has been reported only with anti–programmed cell death 1 or anti–cytotoxic T lymphocyte antigen 4 therapies but never with anti–programmed cell death ligand 1 therapy. It is important to report such rare cases to improve diagnosis and management of irAEs.