During five successive lambing seasons between 2006 and 2011, 453 submissions of abortion material, 282 of ovine and 171 of caprine origin, were examined at the Animal Health Service in the Netherlands. Infectious agents as the most plausible cause of the abortion were found in 48 percent of the ovine submissions and in 34 percent of the caprine submissions. Submission of both aborted fetus and placental membranes increased the diagnostic yield of laboratory investigations (17 percent and 21 percent for ovine and caprine submissions, respectively). The main infectious causes of abortion in sheep were Chlamydia abortus, Campylobacter spp., Toxoplasma gondii, Listeria spp., and Yersinia pseudotuberculosis. The main infectious causes of abortion in goats were Coxiella burnetii, Chlamydia abortus, Listeria spp., Toxoplasma gondii, and Campylobacter spp. In 42 percent of the ovine and in 56 percent of the caprine submissions a causal agent was not identified. Furthermore, in 12 percent of the ovine and 10 percent of the caprine submissions evidence of placentitis, indicative of an infectious cause of the abortion, was found, but no infectious agent was identified. Most infectious causes of ovine and caprine abortion have zoonotic potential. Humans, especially pregnant women, who are in close contact with lambing sheep or goats should be aware of the importance of precautionary hygiene measures.