Panic disorder is a common illness that can have serious consequences, including increased long-term mortality. Family and twin studies suggest that it is a genetic disorder and transmission patterns within families are compatible with a hypothesis of a disease gene predisposing to the condition. Recently, it has become possible to locate disease genes causing familial disorders through linkage analysis. A preliminary linkage analysis of panic disorder at the University of Iowa found suggestive but inconclusive evidence of linkage to the alpha-haptoglobin locus on chromosome 16q22. Future strategies for identifying disease genes in anxiety disorders are described.