OBJECTIVE: This study aimed to evaluate the clinical effectiveness of chemotherapy following immune checkpoint inhibitors (ICI). The association between inflammatory and nutritional factors and prognosis has also been investigated. METHODS: We retrospectively reviewed the medical records of recurrent or metastatic head and neck squamous cell carcinoma (RMHNSCC) patients who received chemotherapy following ICI therapy. The response rate and survival after chemotherapy, and nutritional and inflammatory factors, were examined. RESULTS: The ICI before chemotherapy was nivolumab in 36 patients (70.6%) and pembrolizumab in 15 patients (29.4%). The chemotherapy regimens consisted of PTX in 32 patients (62.7%), PTX + Cmab in 9 (17.6%), and S1 in 10 (19.6%). The median overall survival (OS) was 20 months (95% CI 12-25), the estimated 12-month OS rate was 63.3%, the median progression-free survival (PFS) was 5 months (CI 4-6), and the 12-month PFS estimate was 8.9%. Univariate analysis significantly correlated Neutrophil-to-Lymphocyte Ratio (NLR), platelet-to-lymphocyte ratio (PLR), controlling nutritional status score (CONUT), and prognostic nutrition index (PNI) with OS and PFS. Additionally, these factors were significantly correlated with OS and PFS in the log-rank tests. CONCLUSIONS: Chemotherapy following ICI is highly effective. There were no significant differences in the chemotherapy regimens. Inflammatory and nutritional factors may associate with patient prognosis after chemotherapy.