Background and Objectives: Non-small-cell lung cancer (NSCLC) represents approximately 80% of all lung cancers. Unfortunately, at their time of diagnosis, most patients have advanced to unresectable disease with a very poor prognosis. The oriental herbal medicine HangAm-Plus (HAP) has been developed for antitumor purposes, and several previous studies have reported its therapeutic effects. In this study, the efficacy of HAP was evaluated as a third-line treatment for advanced-stage IIIb/IV NSCLC. Methods: The study involved six patients treated at the East- West Cancer Center (EWCC) from April 2010 to October 2011. Inoperable advanced-stage IIIb/IV NSCLC patients received 3,000 or 6,000 mg of HAP on a daily basis over a 12-week period. Computed tomography (CT) scans were obtained from the patients at the time of the initial administration and after 12 weeks of treatment. We observed and analyzed the patients overall survival (OS) and progression-free survival (PFS). Results: Of the six patients, three expired during the study, and the three remaining patients were alive as of October 31, 2011. The OS ranged from 234 to 512 days, with a median survival of 397 days and a one-year survival rate of 66.7%. In the 12-week-interval chest CT assessment, three patients showed stable disease (SD), and the other three showed progressive disease (PD). The PFS of patients ranged from 88 to 512 days, the median PFS being 96 days. Longer OS and PFS were correlated with SD. Although not directly comparable, the OS and the PFS of this study were greater than those of the docetaxel or the best supportive care group in other studies. Conclusion: HAP may prolong the OS and the PFS of inoperable stage IIIb/IV NSCLC patients without significant adverse effects. In the future, more controlled clinical trials with larger samples from multi-centers should be conducted to evaluate the efficacy and the safety of HAP.