When the tumor-tissue-based EGFR gene results were regarded as the gold standard of diagnosis, the sensitivity of ddPCR in detecting plasma cfDNA EGFR Exon 19 del and Exon 21 L858R mutations was 61.3%, the specificity was 96.7%, and the consistency rate for both mutations was 81.4% (κ = 0.605, 95% confidence interval (CI): 0.501-0.706, P < 0.0001). The gene discussed is EGFR; the disease is neoplasm.