PURPOSE: Colon anastomotic leakage remains a serious and common surgical complication. Animal models are valuable to determine the pathophysiological mechanisms and to evaluate possible methods of prevention. The aim of this study was to develop an optimal model of clinical colon anastomotic leakage in a technically insufficient anastomosis in the mouse. METHODS: A total of 110 mice were used in three pilot studies (1-3) and two experiments (A, B). Due to the high complication rates, the analgesic regimen and surgical techniques were changed throughout the pilot studies/experiments. In the final successful experiment (B), eight and four absorbable sutures were used in the control and intervention anastomoses, respectively, and buprenorphine in chocolate spread was used for pain treatment. RESULTS: In the final model (experiment B), significantly more animals in the intervention group had clinical anastomotic leakage compared with controls (40 vs. 0 %, p = 0.003). The weight loss was greater and the wellness score was also lower in these animals (p < 0.001). The breaking strength of the anastomoses was not significantly different between the control group [0.55 N ± 0.09] and intervention group [0.49 N ± 0.15] (p = 0.091). CONCLUSIONS: This mouse model closely mimics clinical colon anastomotic leakage in humans. The model is of high clinical relevance, since anastomotic leakage has a similar cause, incidence and manifestations in humans.