The present paper deals with the occurrence of Legionella bacteria in a variety of man-made environmentalwaters, including whirlpool bathes, cooling towers and others, from April 1996 to November2000 in the eastern part of Japan around Tokyo area. A total of 2, 895 water samples were examinedfor the possible occurrence of Legionella and 904 (31%) were demonstrated to be positive. Among the various water sources, Legionella were frequently detected both in whirlpool bathes andin cooling towers, of which detection rates were 48% and 46%, respectively. More precisely, occurrenceof Legionella was higher in private-use whirlpool bathes than those for public-use; namely, thepositive rate was 71% in bathes accommodated in private houses, 63% in company's club houses, 62% in company dormitories for employees, and 51%in old-people's homes. Occurrence of Legionella, onthe other hand, was less common (≤30%) in bathes for public-use such as those installed in hotelsand in hot spring facilities. Typing of L. pneumophila serogroups revealed that SG5 (34%) was dominantin whirlpool bath waters followed by SG3 (22%), whereas SG1 (32%) was dominantly found incooling tower waters.