Rapidly changing market conditions, growing competitive pressure and tremendous technological progress led companies to the insight to better understand the needs of their customers and focus on the significance of existing customer relationships. Though, a considerable number of corporations are confronted with serious problems when it comes to concrete implementation and evaluation of Customer Relationship Management (CRM) systems, which in turn results in increased failure rates. Hence, the objective of the present paper is to show critical success factors, barriers as well as challenges for a CRM implementation and evaluation, which enables a systematic realization of the CRM concept and, thus, can contribute to the achievement of the set entrepreneurial goals. Consequently, this paper identifies several critical success factors for CRM projects based on qualitative interviews with Managing Directors, Marketing Managers and CRM Project Managers who have executed CRM projects in their organisations. Among other things, effective project management, methods of employee training, appropriate data quality and internal corporate communication play a key role in the success of CRM systems. Through the conducted interviews, additional critical success factors could be identified, which have not yet been sufficiently covered in the literature.