Dissemination levels of Borrelia sp. isolated from a natural population of Ornithodoros savignyi in Egypt were assessed in various organs of the infected female tick reared at three different temperatures.  Results of the present investigation showed that the extrinsic incubation temperature at which the infected tick was reared (EI) was crucial in affecting borrelial dissemination levels in different organs including gut, salivary glands, coxal organ, ovaries and hemolymph.  The increase of EI from 17^oC to 27^oC and 37^oC increased the infection rates (IRs) and mean number (no.) of spirochetes localized in different organs.  Also, it enhanced the appearance, prolonged persistence and delayed disappearance of spirochetes in most of the organs tested throughout the period of study (90 days after infective meal).