Cancer treatment has so far been restricted to cytotoxic and hormonal agents. These have been of limited value in their efficacy and their toxicity profile. A new era of targeted therapies is rapidly evolving. A key target being actively pursued is the receptor tyrosine kinase. Several compounds that inhibit this target are in preclinical and clinical development. These compounds broadly fall into two categories: monoclonal antibodies and small-molecule inhibitors. The common targets are epidermal growth factor receptor, Bcr-Abl tyrosine kinase, vascular endothelial growth factor, fibroblast growth factor receptor, and platelet-derived growth factor. Two of these compounds, trastuzumab and imatinib mesylate, have been approved by the US Food and Drug Administration for use in specific indications. Other uses are being tested, such as imatinib for gastrointestinal stromal tumor. These compounds will alter cancer care as adjuncts to currently available treatment options.