The aim of this article is to use the Critical To Quality (CTQ) tree, one of the basic tool of Six Sigma concepts, as a decoder that will translate the customers' quality inspection language, their needs and requirements for measurable requirements. The aim of the research was to develop a set of metrics that will be easy to measure and evaluate by managers and which will be the basis to take improving action of quality inspection processes. The paper described the idea of the CTQ tree as a tool for decoding customer language specification for the product, service or process. The procedure of the CTQ elaboration tree was used to create the critical to quality inspection tree, marked as CTQI. Customers of quality inspection process were specified. Their main needs were recalled in relation to quality inspection process (“good”, “fast”, “cheap”) and two of these needs (“good” and “fast”) were referenced to the basic inspection tasks related to the management of nonoconforming products and nonconformities. It was used the "levers" as tool of CTQ tree to find elements of identified requirements, which was used in the next step to identify the measures and indicators for the quality inspection assessment. The set of indicators were elaborated which allow to determine by quality inspection managers the current level of fulfillment customers’ needs and requirements, and based on this analysis take the decisions about the improvement of quality inspection process.