In spite of the dramatic improvements obtained with EGFR-TKIs in patients affected by NSCLC with activating mutations of EGFR, a fraction of these patients (about 30%) do not respond to EGFR-TKIs or achieve a response of short duration. It has been suggested that these patients may be affected by additional mutations that confer resistance to EGFR-TKIs in spite of the presence of activating mutations of the EGFR gene. Pre-clinical studies show that the addition of chemotherapy to gefitinib may result in increased anti-proliferative activity, and subsequent clinical studies suggest that the synergic activity of gefitinib and chemotherapy can depend from the employed schedules (concurrent versus sequential). Additionally, data from phase I trials of gefitinib plus vinorelbine revealed a high incidence of severe hematological toxicity with concurrent administration, while sequential schedules resulted in a more manageable safety profile.