This paper describes methods for testing model wind turbines in wind tunnels based on published data and the experience gained by the author through having tested many different wind turbines in wind tunnels at the University of Auckland. Wind tunnels can be used to determine the performance of small wind turbines at full scale, or larger wind turbines at reduced scale. Such experiments need to be done with care as one needs to be aware of issues regarding blockage, the effect of Reynolds number, and being able to control the speed of the turbine so that is power coefficient can be obtained over a suitable range of tip speed ratios. With rotating machinery, it is also important to have a regard to safety, so the models have to be made with care and a stress analysis carried out to ensure that the material properties are not exceeded during the testing. It is found that wind tunnel testing is a useful way of determining experimentally the performance of wind turbines in order to predict the power output, and for obtaining data to validate theoretical or numerical model predictions.