Medium-sized companies usually operate in various supply chains. Hence the resulting risks should be accounted for adequately. As prerequisite for a successful realization an appropriate risk definition is to be stated. The presented ideal type of a process allows the management of internal as well as external risks. To support a practical implementation numerous recommendations for action are presented in the text. The focus is placed on a model for cost optimal planning and controlling of purchase order quantity and safety stock. An example, which illustrates the positive impact of the co-operation in risk management along the supply chain, completes the paper.