Mutations in the epidermal growth factor receptor occur frequently in a number of human tumours including gliomas, non-small-cell lung carcinomas, ovarian carcinomas and prostate carcinomas. The type III epidermal growth factor receptor mutation (variously named EGFRvIII, de2-7 EGFR or AEGFR), which lacks a portion of the extracellular ligand binding domain, is the most common. Here, we review the current status with regard to the role of EGFRvIII in human cancers. A detailed discussion of the formation of EGFRvIII and its structure at the protein level are likewise included along with a discussion of its more functional roles. The design and use (preclinical and clinical) of small molecule inhibitors, antibodies, and antisense oligonucleotides against wild-type EGFR are considered in detail as these strategies can be directly adapted to target EGFRvIII. Finally, the status of EGFRvIII targeted therapy is reviewed.