Countermeasures involving changes in management practices which are suitable for use in semi-natural ecosystems are described. Most of the relevant information relates to radiocaesium, but the applicability for some other radionuclides has also been evaluated. Improved live-monitoring techniques for radiocaesium, developed since the Chernobyl accident, allow the identification of animals whose contamination levels exceed the intervention limits, so that countermeasures can be effectively chosen and targeted. Generally the most effective approach for domesticated and semi-domesticated animals is either to remove contaminated animals from the affected area or to provide uncontaminated feed. Uncontaminated feed is given continuously for dairy animals or in the final fattening stages for meat-producing animals. The introduction of other effective changes in management practices, such as changing hunting seasons for game, or slaughtering at a time of year when the animals have been grazing on less contaminated herbage, depends on a good understanding of the behaviour of radionuclides in these ecosystems. In practice, the most effective countermeasures which can be used to reduce radionuclide contamination of animals in semi-natural ecosystems will be obtained by a combination of both management changes and the use of chemical binders to prevent gut absorption.