Since many years Knowledge Management Maturity Models (KMMM) have been described as a way to classify the level of knowledge management (KM) in organizations. These models assume that more KM leads to more innovation and thus improves corporate success. Although some of these models have been developed based on case studies, larger scale empirical verifications are scarce. The purpose of this paper is to investigate in how far KMMM can be applied in corporate practice, which factors influence the KM maturity of organizations and if KM maturity is related to corporate success. The paper is based on an online survey of 74 northern German companies. The results show that the application of KM is most evident in the area of technology. Whereas all of the participating organisations use IT to support their KM activities, it is mainly the integration of these systems that leaves room for improvement. In the KM areas of process as well as people, KM is merely partly implemented. Only few of the responding companies have established the position of a knowledge manager, provide a specific budget for KM activities, or integrate KM objectives in their corporate strategy. Consequently, the overall KM maturity levels are assessed as fairly low. Additionally, a positive relation between the accomplished KMM level and employees' participation in KM as well as the innovation success is found. The relation between KMM levels and the financial success does not show any significance. The paper is one of the first which empirically investigates the relations of KM maturity levels to innovation and corporate success. Thus, it provides the foundation for a further development of KMMM and helps organizations to position their KM activities more effectively.