A 2.5-year-old intact female hamster (Phodopus campbelli) was referred to the VMTH of NCHU on May 7th, 2013 for a swelling of left abdomen and signi¯cant decrease in appetite. Physical examination revealed the enlarged abdomen slightly a®ected the patient's mobility. Ā rm mass was palpated in the left abdominal cavity. Tentative diagnosis was an abdominal mass. An exploratory laparotomy and splenectomy was performed together with the removal of a mass of 1 Â 1 Â 0:8 cm in size and 3.6 g in weight. Grossly, the mass was well capsulated and covered by a sac which¯lled with blood-like discharge. Histologically, diagnoses were made according to the results of hematoxylin and eosin, Masson's trichrome and vimentin immunohistochemistry stained sections. Based on the histological characteristics, the¯nal diagnosis was a splenic¯brosarcoma in a Campbell's hamster. The patient is fully recovered after surgery but the hamster died of natural causes four months later.A 2.5-year-old intact female hamster was referred to the VMTH of NCHU on May 7, 2013 with poor appetite and mobility. The hamster was presented with onset of anorexia during a previous visit to another veterinary hospital one month ago. The owners had also noted there was a large and¯rm swelling in the left abdomen of the hamster. §