Thirty-two cats referred to the Feline Studies Centre between June 1987 and October 1988, and 14 in-contact cats, were found to be infected with feline immunodeficiency virus. Most of the 46 cats were non-pedigree and free ranging; 27 were male (19 neutered) and 19 were female (18 neutered). Their ages ranged from one to 17 years and the average age was 5.8 years. The most common clinical signs were lethargy, inappetence, weight loss, pyrexia and lymphadenopathy; most cases had multiple abnormalities. Other common signs were gingivitis, diarrhoea, rhinitis and ocular discharge. Eight cats had neoplasia. The commonest haematological abnormalities were anaemia, neutropenia, lymphopenia and monocytosis. Eight cats had lymphocytosis; seven of these were in a single house-hold. Several cats had high serum globulin levels and half of those tested had high IgG levels. Seven cats had no detectable antibody to feline immunodeficiency virus even though the virus was cultured from the peripheral blood lymphocytes. During follow-up for up to 60 weeks one cat died and 23 were destroyed on humane grounds.