To investigate the reliability of ESD protection in smart power integrated circuits the ESD experiments are performed and degradation is analyzed by low frequency noise measurements. Combining the noise results with further failure analysis analytical methods we have examined a location and the nature of defects. Special attention was dedicated to analysis of latent defects. The possibility to apply noise as reliability indicator for repetitive testing and for use in high volume production are also discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)