 Epidermal growth factor receptor tyrosine kinase inhibitors EGFR TKIs such as erlotinib have proved effective in second or third line therapy for advanced non-small cell lung cancerNSCLC.It is well tolerated without the side effects usually associated with chemotherapy. The mutations in EGFR exons 19 or 21 have been reported to be associated with efficacy of EGFR TKIs.Based on the encouraging preliminary results from the Spanish lung cancer group prospective study reported that the efficacy of Tarceva as first line treatment for metastatic NSCLC patients with EGFR mutation would delay disease progression,prolong overall survival and be well tolerated, medium Progression-free survivalPFS was around 12 months and OS reach 24 months,our study is designed to compare PFS between the patients with mutant EGFR treated by gemcitabinecarboplatin and those by erlotinib in the first-line setting. We assumed 11 months of PFS on Tarceva arm versus 6 months on chemotherapy arm with a0.025alpha-spend for an interim analysis, 80 power and 12 months enrolment period, 12 months FU duration to calculate the sample size. The sample size is 69 pairs. Considering about 10 drop-out rate, the final sample size is 152 patients.So, chemo-naive staged IIIbIV patients with EGFR mutations in exon 19 or 21 will be enrolled into this open-label, randomized,multicenter phase III study. 