Since 2006, several varieties of transgenic Bt maize have been approved for commercial cultivation in Germany. The German regulatory framework for growing these crops comprises moderate ex-ante regulations as well as strict ex-post liability rules to protect conventional and organic farming from possible economic damages caused by transgenic plants and to ensure coexistence. These regulations, however, impose additional costs on those farmers who intend to plant Bt maize. This article addresses the question of how Bt maize-growing farmers perceive the additional costs of regulation and whether coordination or cooperation takes place in order to diminish these costs. In 2006, the authors carried out a case study in the Oderbruch region (Brandenburg, Germany) comprised of eight Bt maize farms and six adjacent non-Bt maize farms. The case study revealed that the costs arising from ex-ante regulations and ex-post liability were only of minor importance to the Bt maize-growing farmers. The predominantly large farms chose intra-farm coordination to manage the construction of buffer zones within their own fields and to avoid the planting of Bt maize close to their neighbors. Inter-farm coordination or cooperation with adjacent farmers was not regarded as necessary to achieve coexistence.