The aim of the study is to evaluate the customer complaints reported to catering services companies (CSC) and to determine the food safety subjects that these companies should focuson as a result of this evaluation. The study was conducted on 3 various CSC customers operating in Istanbul and data were collected in 2019 through Customer Satisfaction Management System (CSMS -ISO 10002:2018). A total of 1221 customer complaints received by ISO 10002:2018 were classified under 4 main headings (Food Safety, Quality, Delivery and Menu) and 13 sub-headings, and the results were tested with frequency analysis. The complaints were caused by 33.58% from food delivery, 30.88% from quality, 25.47% from food safety and 10.07% from menu, respectively. It was determined that the priority in complaints about food safety was physical risk factors with a rate of 67.2% and then biological risk factors with a rate of 32.8%. Among these complaints, factors related to food safety are a situation that reduces the credibility of the company as they directly affect health. Besides, the presence of risk factors related to food safety that cause customer complaints concerns public health, it is not only an individual but also social problem. As a result, it has been determined that catering customers have food safety problems and complaints. It may be suggested that catering services companies work on the specified food safety complaint subjects in order to ensure customer satisfaction, ISO 10002:2018 effectively manages customer relations and finally develop and implement effective food safety management strategies.