Background <p>Beta-human chorionic gonadotropin (β-hCG) is frequently overexpressed in germ cell and trophoblastic tumors as well as various solid tumors; however, the presence of high levels of serum β-hCG is very rare in patients with non-small cell lung cancer.</p> Case Description <p>This report serves as a case study of an 84-year-old, non-smoking female who was diagnosed with advanced lung adenocarcinoma with bone and pleural metastases. The serum and pleural fluid β-hCG levels were significantly increased (2,618 mIU/ml and &gt; 10,000 mIU/ml, respectively). Next-generation sequencing of the cancerous lung tissue revealed a mutation in the epidermal growth factor receptor (EGFR) gene, consistent with a deletion of exon 19. The patient was treated with gefitinib, an EGFR tyrosine kinase inhibitor, which resulted in a partial response. Unfortunately, during treatment, the patient developed interstitial lung disease and a pulmonary infection. Despite receiving treatment with steroids and antibiotics, the condition worsened, and the patient ultimately succumbed to the illness and passed away. The overall survival was 77 days.</p> Conclusions <p>This is the first report of pulmonary adenocarcinoma with both high serum β-hCG levels and an EGFR mutation.</p>