Peninsular Malaysia and Tasmania possess wilderness rain forests of great value to mankind. In both regions, however, undisturbed forests are dwindling and competition for the resources of the remaining forest areas is increasing. One result has been land use conflicts, some of them intense and prolonged. Two recent controversies—one over the logging of tropical forests in the Endau-Rompin region of southern Peninsular Malaysia, the other concerning a dam project in the Gordon-Franklin wilderness in south-west Tasmania—are described, analysed and compared. The authors describe the significance and value of the two wilderness areas, discuss the two controversies as ‘environmental issues’, examine the tactics employed by environmental pressure groups and explain how the two disputes were influenced by federal-state relations and certain constitutional considerations.