The paper presents a method for assessing the accuracy of in-line inspection (ILI) results. The main objective of the method is to determine whether the measurements obtained by ILI are adequate and acceptable. If too few measured dimensions of defect parameters (for example, their depths) fall within the range of values obtained using verification results, this indicates that the ILI tool incorrectly estimated the actual data. Thus, the lower (upper) limit is estimated for the number of satisfactory (unsatisfactory) ILI tool measurements.