Digestive fistulas are a major complication after digestive surgery. Anastomotic leakage increases the hospitalization time, the prognosis and survival rate after colorectal surgical interventions.The factors involved are either systemic (determined by the patients’ co-morbidities), or local (vicious surgical technique or the injuries produced by the disease that requires the anastomosis). Although there are many studies regarding the risk factors of anastomotic leaks, there is no consensus for the role played by each one of them in the healing process of digestive sutures. Most authors sustain that the importance of systemic factors is secondary, the main role being played by the surgeon and the local conditions of the anastomosis.Knowledge of the risk factors can lead to new methods of reducing the incidence of anastomotic leaks by improving vascularization, limiting the tension and the duration of surgery, and by new surgical techniques used for digestive sutures.