Due to the often almost unmanageable variety of products on online marketplaces, online customer reviews (OCRs) have long since established themselves as an important source of inspiration and information, as well as a decision-making aid for online shopping. This applies not least to Amazon.com , the world’s largest online retailer and leading pioneer of OCRs. However, the importance of reviews published on Amazon goes beyond Amazon: A considerable number of prospective customers who go online to buy products use Amazon as their first source of information. This paper provides the beginnings of a response to the question of how reliable customer ratings and reviews on Amazon are as a decision-making aid. It focuses on a comparative analysis of customer ratings and reviews on Amazon.de with the corresponding test results from „Stiftung Warentest“. This leading German non-profit consumer organization concentrates on the objectifiable features of the individual offers and thus provides a relevant counterpoint to the very personal ratings of Amazon customers.