This International Standard specifies a method for the determination of lethal as well as sublethal effects of contaminated sediments on the ostracod crustacean Heterocypris incongruens after 6 d exposure. The method is applicable not only to fresh water sediments, but also by extension to solid wastes and soils after addition of (uncontaminated) water. The method can also be applied to chemicals or preparations which are spiked into a reference sediment. This International Standard is not applicable to the testing of sediments from the estuarine or marine environment.