After an inspection tour to farms and abattoirs in Australia and New Zealand, three Japanese persons simultaneously developed febrile illnesses in Japan. They generally had slight fever and general fatigue, followed by thrombocytopenia and hepatic dysfunction. However, no respiratory symptoms were observed. In one of the cases, severe thrombocytopenia (1.3 x 10(4)/microliter) and high fever up to 40 degrees C were observed. These clinical symptoms were compatible with Q fever. All of the cases showed four hold-elevations of IgM and IgG against Coxiella burnetii phase II between acute and convalescent sera by a serological test. C. burentii-DNA was also detected in the serum of one patient. Minocycline was highly effective in all cases. This report illustrates the typical clinical courses of acute Q fever.