ANAEMIA is a common presenting sign in feline medicine. More than 10 per cent of cats referred to our clinics have anaemia, and 7 per cent have profound anaemia, with a haemoglobin concentration on presentation of less than 8 00 g/dl. Feline anaemia can also be a frustrating clinical problem. A large proportion of cases remain undiagnosed and the prognosis in those in which a diagnosis is reached is remarkably poor: more than 80 per cent of cats with anaemia referred to us have died within 18 months of presentation. There are a number of reasons why feline anaemia is such a difficult problem. Cats have a well developed ability to adapt their lifestyle to compensate for disease processes and therefore clinical signs may not become apparent until the anaemia is profound. In addition, poor exercise tolerance is one of the most important early presenting signs in anaemia in other species, but this is rarely noticed by cat owners. Anaemia is a serious problem also because of the nature of the underlying disease processes with which it is commonly associated in cats, such as feline leukaemia virus infection and neoplasms. Anaemia in the cat, as in any other species, is not a diagnosis. Rather, anaemia is a clinical sign associated with a number of conditions and if the prognosis is to be assessed correctly and the appropriate treatment is to be instituted it is vital that the animal receives a thorough clinical and laboratory investigation.