The aim of this study was to better understand the epidemiology of five major reproductive pathogens in semi-intensive lamb-producing flocks in North-West Spain. Two thousand four hundred serum samples were collected from 44 flocks, and several factors were studied to assess their influence on seropositivity.Farms that tested seropositive for more than one pathogen were common (84.1%), but seroprevalence was high only for Toxoplasma gondii (38.1%), and low for the other four pathogens, namely, Neospora caninum (5.5%), Coxiella burnetii (4.0%), Chlamydia abortus (3.9%) and Pestivirus (2.3%). Farm level exposure was highest for T. gondii and N. caninum (100% and 72.7%, respectively). For both of these pathogens, and for C. burnetii, seropositivity was associated with age and area. Farm level exposure was lowest for Pestivirus and C. abortus (13.6% and 18.2%, respectively), and, for the latter, seropositivity was principally related to flock size.