Of the anxiety disorders, panic disorder (PD) has been the most extensively studied from a genetic standpoint. Results of family studies have consistently demonstrated that PD runs in families, and twin studies indicate that genes contribute to this familiality. However, phenotypic and genetic complexity has made finding the specific genes involved in PD a challenge. There is still uncertainty about how best to define the phenotype for genetic studies and whether it is the clinical phenotype of PD or more latent psychologic and biologic traits that are inherited. To date, molecular genetic studies have suggested some chromosomal regions and genes that may contribute to risk, but none of these have been established. We review the genetic epidemiology of PD as well as recent molecular genetic studies of the disorder, and conclude with a discussion of promising strategies that attempt to uncover specific genetic loci involved in the etiology of PD.