A total of 289 Rhipicephalus (Boophilus) microplus Canestrini (Acari: Ixodidae) collected from cattle in Xiamen city of Fujian province, southeastern China, were tested for ehrlichial agents by nested polymerase chain reaction assay. Twenty-seven (9.3%) ticks from seven cattle were found positive for Ehrlichia. The polymerase chain reaction products from positive samples were sequenced and found identical with each other. The 1458-bp nucleotide sequence of ehrlichial 16S rRNA gene was obtained and showed the greatest levels of sequence similarity to 16S rRNA gene sequences of the Ehrlichia spp. detected in ticks near Thai-Myanmar-Vietnam border and that in Tibet, China, differing only 2 and 4 bp, respectively. Sequence comparison of the 16S rRNA gene with the members of the genus Ehrlichia reveals that this ehrlichial agent differed from the sequences of E. chaffeensis in ticks from southeastern China by 17 bp, showing close relation to E. chaffeensis. This was the first report on ehrlichial pathogens in R. (Boophilus) microplus from cattle in southeastern China. The spatial distance between Fujian province and Tibet is more, whereas the ehrlichial agents from both regions are highly homologous. The veterinary and public health significances of the agent deserve further investigation.