A sheep farm housing 124 animals, of which 68 were ewes having history of abortion and placenta retention, were informed. In total, 19 vaginal swabs taken from aborted ewes, 3 fetuses, 4 placentas, and 1 drinking water sample were investigated microbiologically. A total of 60 blood samples (27 from aborted ewes, 18 from pregnant ewes and 15 from healthy neonate ewes) were investigated serologically. Eighteen Aeromonas hydrophila strains were isolated: 13 from vaginal swabs, 3 from fetuses, 1 from placenta and 1 from drinking water. Protein profiles of A. hydrophila strains were determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Of the 27 aborted ewes sera, 7 sera were found to be positive in rapid agglutination test (RAT) with prepared RAT antigen from A. hydrophila. A. hydrophila strains were determined to be resistant to penicillin G, erythromycin and gentamicin. The most effective antibiotics were amoxycillin and enrofloxacin. A. hydrophila is likely to interfere with the normal development of the fetus, especially if pregnancy and other stressing factors occur during gestation. © 2005 Elsevier B.V. All rights reserved.