Objective: Gastric ulcers in green iguanas have not been described yet. In this first report this disease is presented. Material and methods: Clinical symptoms and diagnostic options of gastric ulcers in three green iguanas are described. Possible causes are discussed. Results: The unspecific clinical signs comprise apathy, anaemia, anorexia and to some extent, vomiting. Stress, e.g. due to hospitalisation and the application of non-steroidal anti-inflammatory drugs may lead to gastric ulcers in green iguanas. Conclusions: Minimizing of stress (short hospitalisation, minimal handling, ideal housing conditions) and prophylactic use of antacids and histamine type 2 receptor antagonists are recommended. Generally, gastric ulcers in herbivorous reptiles should be taken into consideration as a secondary disease.