Detailed field surveys were undertaken in selected areas in the Central Region of Malawi starting in August 1981. The areas chosen following verbal enquiries and a questionnaire had recently suspected cases of pig disease. Each village in these selected areas was visited and each individual pig farmer asked how many pigs he owned, whether any had died and if so details of the numbers which died with dates, clinical signs and duration of illness. From this information those deaths which seemed likely to have been the result of ASF were recorded and pigs in which the cause of death was not clear were excluded. A presumptive diagnosis was based on an assessment of clinical and epidemiological details consistent with those reported for ASF elsewhere in Africa.