Clinical experience with the EGFR-TKI gefitinib in Asian patients with NSCLC will be reviewed, both in patients who have previously failed chemotherapy and in the first-line setting (gefitinib is currently not licensed for first-line treatment). Tolerability and specific adverse events in patients of Asian origin will be discussed. Differing objective response rates between patients of Asian and non-Asian origin when treated with gefitinib (and standard cytotoxics) will also be discussed along with EGFR mutations and drug resistance. Reports of Phase II/III clinical experience with gefitinib 250 mg/day in Asia were identified by searching in Medline and ASCO databases for publications between 1993 and 2008. Defined search criteria included (gefitinib OR Iressa OR ZD1839) AND NSCLC AND (Asia OR Japan OR China OR Taiwan OR Korea) or 'Clinical trial' type, with additional searches, including AND 'interstitial lung disease (ILD)' or 'EGFR mutation'. Numerous Phase II/III trials including patients of Asian origin with previously treated advanced NSCLC report a consistent clinical benefit of gefitinib. Gefitinib is generally well tolerated by patients with NSCLC although the incidence of ILD in Japanese patients must be noted. Studies analyzing EGFR mutations indicate that these mutations occur at a much higher rate in patients of Asian origin than in non-Asian patients. Data from several studies indicate that EGFR mutation-positive patients of Asian origin have better efficacy outcomes with first-line gefitinib when compared with those who are EGFR mutation-negative. Research is ongoing to evaluate the role of tailoring patients' treatment according to their genetic phenotype.