The present work deals with the surface defects of drawn wire products and investigates improvements in their finding. As an introduction, the operational risk analysis is explained and for a better understanding of the importance of failures, relevant examples for the wire industry are provided. The consideration of the core topic "wire defect" begins with a sorting of flaws, found in products, on geometric features. On one hand, to give an overview of the possible flaws and on the other hand, to make a pre-assessment of the geometry-dependent possibilities of detection. The investigation of individual test procedures begins with the already widely implemented eddy current test. After a brief theoretical introduction, possibilities of adaptation to the individual products to achieve better results are discussed and in a practical investigation the dependence of the error signal on the axial failure extent is proved. The sound emission analysis is given special attention in this work. Since this test method is still largely unknown in the wire industry, it is initially attempted to provide a comprehensive introduction to the subject matter. It explains the peculiarities of the procedure as well as the possibilities of the unwanted influencing of the measurement results and offers suggestions for this for their avoidance. This topic is completed with the example of an installation on a drawing machine and the evaluation of the collected data. In addition, the test methods ultrasonic testing and thermographic image analysis are examined for their suitability as an inline test instrument and their advantages and disadvantages with regard to a future implementation in the process are explained. It concludes with an extensive discussion of findings that have emerged in the course of this work.