For the purposes of our investigation, molecular mimicry is defined as similar structures shared by molecules from dissimilar genes or by their protein products. Either the molecules’ linear amino acid sequences or their conformational fit may be shared, even though their origins are as separate as, for example, a virus and a normal host self determinant (Fig. 1). Because guanine cytosine (GC) sequences and introns designed to be spliced away may provide, respectively, false hybridization signals and nonsense homologies, focus on molecular mimicry is necessary at the protein level. Such homologies between proteins have been detected either by use of immunologic reagents, humoral or cellular, that cross-react with two presumably unrelated protein structures, or by computer searches to match proteins described in storage banks. Regardless of the methods used for identification, it is now abundantly clear that molecular mimicry between proteins encoded by numerous microbes and host “self” proteins is a common event. Such data is not only of interest in autoimmunity but also as a likely mechanism by which viral proteins are processed inside cells (Fig. 2; Dales et al. 1983). The cartoon of Fig. 2 attempts to bring together a number of observations including (a) the high incidence of cytoskeletal autoantibodies found in most microbial (viral) infections and (b) increasing observations that viruses may use the cytoskeletal apparatus for their own purposes of trafficking and assembly.