The epidermal growth factor receptor (EGFR) is a transmembrane receptor involved in the regulation of a complex array of essential biological processes such as cell proliferation and survival. Dysregulation of EGFR signaling network has been frequently reported in multiple human cancers and has been associated with the processes of tumor development, growth, proliferation, metastasis and angiogenesis. Inhibition of the EGFR was associated with antitumor effects in preclinical models. On the bases of these data, therapeutics targeting the EGFR were explore in clinical trials. Tarceva (OSI-774, OSI Pharmaceuticals, Uniondale, NY) is a small molecule selective inhibitor of the EGFR tyrosine kinase (TK). In preclinical studies, Tarceva inhibited the phosphorylation of the EGFR in a dose and concentration dependent manner resulting in cell cycle arrest and induction of apoptosis. In in vivo studies, the agent caused tumor growth inhibition and shoved synergistic effects when combined with conventional chemotherapy. Subsequent single agent phase I studies and phase I studies in combination with chemotherapy demonstrated that the agent has a good safety profile and induced tumor growth inhibition in a substantial number of patients with a variety of different solid tumor. Preliminary report from phase II studies confirmed the excellent tolerability of Tarceva as well as showed encouraging preliminary activity. Phase III studies have either been completed or are ongoing in several tumor types such as lung cancer and pancreatic cancer. In summary, Tarceva is a novel inhibitor of the EGFR TK which has shown promising activity in initial studies and is currently undergoing full development as an anticancer drug.