The term risk is understood to be the danger of the occurrence of an undesired, life-threatening event. The probability of this undesired event is greater in the presence of a risk factor than in its absence. In general surgery, these risk factors can be classified into five groups: The environment, the surgeon, the operation per se, the disease, and the patient himself. Abdominal surgery is especially suited to clarify and to illustrate this classification. Some typical risk factors are described, and for each group the measures for risk prevention or risk reduction are discussed.