In this survey for the presence of the feline leukaemia virus (FeLV) in the Singapore domestic cat population, the sera of two different groups of unvaccinated mainly short haired cats which were over 6 months old were sampled. The FeLV enzyme-linked immunoadsorbent assay (ELISA) diagnostic test kit was used to detect the presence of the FeLV group specific (gs) antigens in the blood of cats. Of the 345 clinically healthy cats surveyed, 34 sera (9.9%) were found to be positive and of the group of 123 cats with clinical signs such as chronic wasting, marked by anaemia, anorexia and lethargy, 33 sera (26.8%) were found to be positive. From the time of diagnosis of a viraemia, 70% of cats will die within 20 months. The results are therefore indicative that annually a small proportion of cats in the local environment will die from a FeLV infection. This survey reflects the natural distribution of an infectious oncovirus in a susceptible host population which is unaffected by any control programme to interfere with the normal sequence of events of host virus interactions.