A large number of Ehrlichia-like microorganisms was detected in acinus cells and lumen of salivary glands of host-searching unfed Ixodes ricinus nymphs. The results indicate that Ehrlichia-like microorganisms are able to multiply in the acinus cells and disseminate into acinus lumen before blood-feeding, and that the microorganism can be transmitted into their vertebrate host once salivation begins during the very early period of blood-feeding. Although if the detected Ehrlichia-like microorganisms is one of strains of Ehrlichia phagocytophila remains uncertain, the results may give some clues to the further investigations into the tick relationship of the TBF agent.