Hemiplegic migraine may be familial or sporadic. Both forms share a similar spectrum of clinical presentations and genetic heterogeneity. Current data support the concept that sporadic and familial cases should be thought of as similar, but separate disorders. Sporadic cases are more difficult to diagnose and often require several investigations to rule out more ominous possibilities. Therapeutic options are limited, but future genetic research may elucidate pathophysiologic mechanisms that may, in turn, yield more specific treatments.