Anti-PD-1 and PD-L1 inhibitors are associ- ated with several adverse events, including a spectrum of immune-related adverse effects (irAEs). Neurologic irAEs are uncommon occurrences with varied presentations. The present study presents a case of facial nerve injury irAEs associated with adjuvant pembrolizumab therapy (Keytruda), which exhibited unusual presentations. A 44-year-old male patient with extensive-stage small-cell lung cancer (ES-SCLC) was treated with a 6-cycle etoposide and cisplatin (EP) regimen followed by 200 mg pembrolizumab (Keytruda) intravenously once every 3 weeks. Magnetic resonance imaging (MRI) imaging of the brain revealed that there were abnormal enhancement areas in the left pontine crus, with clear boundaries. The patient terminated the use of pembrolizumab; however, EP chemotherapy continued and he was treated with high-dose hormone therapy with the resolution of neurological symptoms. A total of 40 mg meth- ylprednisolone was administered for 5 days and the patient was then administered oral prednisone tablets (25 mg). After 1 week, the facial symptoms were significantly alleviated. Following hormone therapy, the re-examination of head MRI revealed that the lesion had shrunk and the symptoms had improved. The patient remains disease-free. Facial nerve injury of neurological irAEs is uncommon adverse events in the context of PD-1 inhibitor therapy. The neurotoxicity caused by immune checkpoint inhibitors (ICIs) should be a cause of concern. The early recognition of neurological irAEs is critical for the initiation of specific anti-inflamma- tory agents for the prevention of such events. These events are usually alleviated with hormone therapy, which can distinguish metastatic tumors from neuropathy.