In water environment, it is important to elucidate a correlation between the content of pesticides detected in waste water from golf links and mutagenicity. We investigated seasonal changes of the mutagenicity and measured the content of pesticides in water samples obtained from golf link reservoirs, such as two stations of Uji River basin and three stations of Kizu River basin during one year from spring in 1995 to winter in 1996. The mutagenicity was assayed with Salmonella typhimurium strains TA98 and TA100 in the presence and absence of S9mix. In the water samples obtained from the reservoirs and rivers no seasonal changes were detected. However, indirect frameshift-type or base pair substitution-type mutagens were found. The magnitude of the mutagenicity of water obtained from golf link reservoirs was presumed to be almost the same as that from the rivers. No correlation was shown between the mutagenicity and the contents of pesticides detected. Moreover, concerning water from golf link reservoirs the mutagenicity seemed not to be related with the values used as an index of the quality of water such as COD etc..