To give optimal treatment to the patients with early lung cancer, we are trying to establish two new techniques to select the patients of poor prognosis and sensitive to the chemotherapy. To pick up the patients of poor prognosis nevertheless the early stage of their lung cancer, we are developing a new method to detect cancer cells floating in the peripheral blood flow with RT-PCR using cancer specific mRNA. To choose optimal chemotherapy regimens, we have established a new chemosensitivity testing (collagen gel droplet embedded culture drug sensitivity test: CDDST) for non-small cell lung cancer (NSCLC). Median survival time (MST) of the patients (n = 11) with unresectable NSCLC, who were given optimal chemotherapy according to CDDST, was 15.8 months and MST of those (n = 16) who did not have any sensitive agents according to CDDST was 5.6 months. There was significant difference between these two groups (p = 0.0048; logrank).