A 19 months old Belgian Blue heifer was referred to the Veterinary Clinic of Liege University. The heifer was 2 months pregnant by artificial insemination performed by the farmer, and presented hyperthermia, anorexia and weight loss. Rectal palpation revealed a large, depressible abdominal mass. Diagnosis of parietal fibrinous peritonitis (PFP) was made by ultrasound, revealing a liquid and fibrin filled cavity attached to the abdominal wall. Blood analysis indicated an inflammatory status. Analysis of a PFP fluid sample confirmed bacterial contamination. Treatment, apart from fluids, antibiotics and non-steroidal anti-inflammatory drugs, consisted of surgical drainage and repeated flushing of the cavity. Complete resorption of the cavity was observed after 5 weeks. The heifer remained pregnant but died 7 months later, after elective caesarean section, due to generalized peritonitis. This is the first report of PFP in an animal without a history of laparotomy. The PFP may have been caused by an insemination induced trauma.