Although our study was retrospective in nature and had a relatively small sample size, our results suggest that digital PCR to detect T790M mutation in plasma samples could be an alternative and non-invasive method for patients with EGFR-positive NSCLC resistance to first- or second-generation EGFR-TKIs, especially patients from whom tumor lesions can be collected safely. The gene discussed is EGFR; the disease is neoplasm.