Epidermal growth factor variant III (EGFRvIII) is the most common alteration of the epidermal growth factor (EGF) receptor found in human tumors. It is commonly expressed in glioblastoma multiforme (GBM), where it was initially identified. This constitutively active mutant receptor leads to unregulated growth, survival, invasion, and angiogenesis in cells that express it. EGFRvIII results from an in-frame deletion of exons 2 to 7 resulting in the fusion of exon 1 to exon 8 of the EGF receptor gene creating a novel glycine at the junction in the extracellular amino terminal domain. The juxtaposition of ordinarily distant amino acids in combination with the glycine that forms at the junction leads to a novel tumor-specific epitope that would make an ideal tumor-specific target. A peptide derived from the EGFRvIII junction can be used as a vaccine to prevent or induce the regression of tumors. This peptide vaccine has now proceeded to phase 1 and 2 clinical trials where it has been highly successful and is now undergoing investigation in a larger human clinical trial for patients who have newly diagnosed GBM. In this article, the authors discuss the preclinical data that led to the human trials and the exciting preliminary data from the clinical trials.