A 20-year-old horse was evaluated for symptoms of weight loss, anorexia, fever and lethargy. Clinical examination revealed tachypnea, poor body condition and increased breath sounds on auscultation. Ultrasound showed multiple consolidations on the lungs. Thoracic radiography revealed a severe nodular pattern. The horse was treated with antibiotics, corticoids and supportive medication. Since no improvement was observed, the horse was euthanized. At necropsy, numerous coalescing fibrous nodules were present in the lungs. Histology revealed diffuse interstitial fibrosis and macrophages containing abundant eosinophilic cytoplasm and oval eosinophilic to amphophilic intranuclear inclusion bodies. Tissue samples tested positive for the presence of equine herpes virus 5 (EHV 5) on the basis of the polymerase chain reaction (PCR) test. A diagnosis of equine multinodular pulmonary fibrosis (EMPF) was made. This is the first report of EMPF in Belgium. EMPF can be suspected based on the ultrasonographic, radiographic and histological changes. EMPF is associated with EHV 5, but the etiological role of EHV 5 still remains to be proven.