Blood samples from 153 dogs living in and around Barcelona were assayed for Leishmania infantum and Ehrlichia, Anaplasma, Rickettsia, Bartonella, Hepatozoon, Babesia and Theileria species by PCR amplification of DNA, and the amplicons obtained were sequenced. The prevalence of the infectious agents was L infantum (29.4 per cent), Ehrlichia and Anaplasma species (4.0 per cent), Hepatozoon canis (3.3 per cent), Babesia canis vogeli (2.0 per cent), Babesia gibsoni (2.0 per cent), Babesia canis canis (1.3 per cent) and Theileria annae (0.7 per cent). Coinfections were present in seven of the dogs and they were significantly associated with L infantum infection (P=0.024). There was a significant correlation between clinical signs of illness and the load of L infantum.