Planting Bt transgenic corn in large areas of the environment may lead to European corn borer(ECB) [Ostrinia nubilalis (Hubner)] resistance to Bt toxins. Scientists recommend planting a non-Bt corn refuge of at least 20% of total corn area in close proximity to Bt corn as part of an Insect Resistance Management (IRM) strategy. A partial budget analysis was used to estimate the costs of implementing alternative refuge configurations in the US Corn Belt. A strip configuration is the least cost method of planting a 20% non-Bt corn refuge. A block-U refuge combination is only slightly more costly. The costs are small regardless of configuration choice and it is likely that other considerations, such as potential GMO segregation requirements, will dictate choice of configuration.