The General Agreement on Tariffs and Trade (GATT) sets the rules for international trade in goods and services. One of the main aims of GATT is to remove barriers to trade. Environmental laws can sometimes act as barriers to trade, so GATT places conditions on the use of environmental measures. This study investigates the implications of GATT for New Zealand environmental policy. Findings suggest that GATT is already impacting on options for environmental policy in New Zealand, with the Government reluctant to employ environmental measures that contravene GATT rules. If, in the future, New Zealand attempts to extend the range of environmental policy instruments used, implement higher standards, or adopt a more precautionary approach to environmental policy, GATT may significantly restrict our options.