ABSTRACT. Gaeta N.C., Rizzo H., Meira Jr E.B.S., Pituco E.M., Okuda L.H., Ribeiro C.P. & Gregory L. [Detection of antibodies against pestivirus in sheep with history of reproductive disorder in the State of São Paulo.] Detecção de anticorpos anti-pestivírus em ovinos com histórico de problema reprodutivo no Estado de São Paulo. Revista Brasileira de Medicina Veterinária, 38(2):153-156, 2016. Departamento de Clínica Médica. Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva, 87, Cidade Universitária, São Paulo, SP 05508-270, Brasil. E-mail: email@example.com Pestivirus are responsible for reproductive disorders in sheep and, although they are widely studied in other countries, Brazil lacks information on the prevalence of virus in sheep flocks. To investigate the occurrence of pestiviruses in the State of São Paulo, 268 samples of serum sheep with a history of reproductive problems from 28 properties were collected. Using virusneutralization as the diagnostic technique, it was found two (1%) positive animals, with antibody titer of 20, with both females showing a history of reproductive problems, one with neonatal death and another, showing uterine secretion. Two properties studied showed reactive animals (7%). In five of these (18%), bovine co-creation was observed. There were no associations between any reagent animals and the risk factors studied. This work is one of the pioneers in the study of the prevalence of anti-pestivirus antibodies in Brazilian sheep flocks. The low frequency and low viral titer observed suggest that pestivirus are not an important agent related to the presence of reproductive disorders in sheep herds.