We show by sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blot that the composition of the soluble extracts of salivary glands (SGE-2) of Ornithodoros erraticus and Ornithodoros moubata is similar to that of the saliva (pilocarpine-induced), and that the extracts are a valid source of antigens for the detection of anti-argasid antibodies. It is also shown that the SGE-2s do not vary qualitatively with the developmental stage, physiological status, or sex of the ticks. The antigenic components (at least in O. erraticus) are released into the SGE-2 by the action of enzymes that can be inhibited by phenylmethane sulfonyl fluoride plus EDTA. Most of the components of the SGE-2, except the antigenic ones, are strongly glycosylated. Accordingly, the deglycosylation of the SGE-2s does not affect the recognition of antigenic components by anti-tick sera. In both species, the major components of the SGE-2s or the saliva are not recognized by the corresponding antisera. These nonimmunogenic components could have vaccinal value but not diagnostic interest. Finally, it is shown that the antigens of O. erraticus and O. moubata do not cross-react with one another and that those of the first species are more antigenic than those of the second.