Calcitonin gene-related peptide (CGRP) is a potent neuromodulator and vasodilator. It has been implicated in the pathogenesis of migraine by a number of lines of evidence, although its precise role has yet to be fully defined. Compelling evidence for the importance of CGRP in migraine has been provided by clinical trials with multiple small molecule CGRP receptor antagonists. These clinical studies have shown that blockade of the CGRP receptor can produce antimigraine efficacy comparable to that of the gold standard triptan class of drugs with an incidence of adverse events that appears to be relatively low. The present review describes the discovery and development of these new antimigraine agents and highlights the challenges of identifying orally acting drugs that target a family B G-protein-coupled receptor.