Transitions of usage and detection or concentration changes were summarized for the representative pesticides which had become research objects in water, fish and shellfish from Lake Biwa since 1960's. The concentrations of HCH and DDT in corbicula from Lake Biwa were surveyed for the first time in 1963, and similarly in 1966 ～1976 for those in Isaza from northern basin of Lake Biwa. Further, the concentrations of organochlorine pesticides such as HCH, DDT and chlordane in crucian carp and Japanese dace from Lake Biwa have been surveyed since 1975. It was clarified by the concentration survey of HCH isomers in water from Lake Biwa and Yodo River Basin in 1975 that the order of concentration ratios of HCH isomers (β＞α＞γ＞δ) in water from all areas of Lake Biwa was different from that (α＞β＞γ＞δ) in water from normal seas or rivers and the percentage of β-HCH in the water from Lake Biwa was high, 75 %. A large quantity of PCP was used as a paddy herbicide in Japan in 1960's and a great damage was caused to fish and shellfish in all littoral zone of Lake Biwa in 1962. CNP was registered as a herbicide in 1965 and had been used in Shiga Prefecture since 1966. The concentrations of CNP in Isaza from northern basin of Lake Biwa were surveyed in 1963 ～1987. Concentration survey data in water, fish and shellfish from Lake Biwa in 2000 ～2014 were summarized for insecticides (diazinon, fenitrothion and fenobucarb), fungicides (iprobenfos and isoprothiolane) and herbicides (molinate, bromobutide, simetryn and mefenacet) which were registered as pesticides in Japan from 1955 to 1986 and continuously used in the present.
