This report describes a case of nonfatal idiopathic splenic haematoma and pancytopenia in a female ass, a condition that has not been previously reported in this species. A 12-year-old female ass weighing 225 kg was presented with signs of anorexia, depression and prominent abdominal distension. At the onset of clinical signs there was evidence of anaemia, leucopenia and thrombocytopenia. A large mass was palpated per rectum. The mass was confluent with the spleen and extended across the entire width of the abdomen. Percutaneous transabdominal ultrasonography and laparoscopy under general anaesthesia confirmed the diagnosis of splenic haematoma. The ass was treated initially with intravenous polyionic fluids; vitamins, trace elements and aminoacids; clanobutin; and penicillin and gentamicin, and was transfused with whole blood. After 5 days of hospitalisation the ass appeared brighter, and after 10 days the animal was discharged to recuperate at pasture. Six months later the animal's demeanour and appetite had improved. Repeat ultrasonographic examination showed persistence of the mass, but its thickness had decreased by 2 to 3 cm. A small mineralised area suggesting organisation of the haematoma was also detected. The haematological parameters had returned to normal values and the ass was clinically normal.