A case of peritoneal cystic echinococcosis (CE) in a domestic cat was reported from Queensland, Australia. Physical examination of the cat indicated a large, distended abdomen, which when palpated appeared to be fluid-filled. Ultrasonography showed numerous cysts with hyperechoic walls and anechoic contents within the cat's abdominal cavity. Whole mount microscopy and histology, together with molecular identification of the contents based on mitochondrial DNA gene sequencing indicated that the causative agent was Echinococcus granulosus (sensu stricto) (genotype G1). Moreover, the cat was also found infected with Feline Leukemia Virus (FeLV). It is surmised that FeLV-induced immunosuppression could have led to the development of CE in this cat. This is the first report of CE in a FeLV infected cat in Australia.