A presumptive case of Murray Valley encephalitis (MVE) acquired in Alice Springs in March 1997 is reported. The patient subsequently died in Mackay. The diagnosis of Murray Valley encephalitis was supported by the detection of flavivirus IgM in cerebrospinal fluid. Low titres of IgM specific to Murray Valley encephalitis and Alfuy were detected in a single serum sample. The patient's travel movements indicate that his infection was acquired in the Alice Springs vicinity. This conclusion was further supported by the detection of Murray Valley encephalitis activity in sentinel animals in the area and by the presence of large numbers of the principal mosquito vector of Murray Valley encephalitis in the Northern Territory.