OBJECTIVE: Pulmonary pleomorphic carcinoma is a relatively rare and aggressive subtype of non-small cell lung cancer (NSCLC), with a poor prognosis and early recurrence, and is resistant to conventional therapies. This study investigated the efficacy of immune checkpoint inhibitors (ICIs) in improving the survival outcomes of patients with pulmonary pleomorphic carcinoma with postoperative recurrence. METHODS: We conducted a retrospective analysis of 71 patients with pulmonary pleomorphic carcinoma who underwent pulmonary resection at Tokyo Medical University Hospital between 2008 and 2022. Clinicopathological data, programmed cell death ligand 1 (PD-L1) expression, and postoperative recurrence treatment outcomes were reviewed. RESULTS: Among the 71 patients with pulmonary pleomorphic carcinoma, the 5-year overall survival (OS) rate was 48.6 %, and high PD-L1 expression (28-8 clone) was observed in 87 %. The median recurrence-free survival (RFS) was 19.4 months, and postoperative recurrence occurred in 38 patients (54 %). Treatment after recurrence was administered to 24 patients (63 %), and immunotherapy was administered to 10 patients (26 %). In patients treated with ICI, the overall response rate (ORR) was significantly higher (50 %) compared to those treated without ICI (7 %). The median survival time after relapse was notably longer in the ICI-treated group (83.9 months), compared to the non-ICI group (10.1 months). CONCLUSION: ICIs significantly improve survival outcomes in patients with recurrent pulmonary pleomorphic carcinoma, particularly in those with high PD-L1 expression. Early postoperative recurrence and rapid progression have been observed, making therapeutic intervention challenging. Close follow-up is crucial, and ICIs become a pivotal treatment option for managing this highly aggressive cancer.