One of the issues regarding the misclassification in case-control studies is whether the misclassification error rates are the same for both cases and controls. Currently, a common practice is to assume that the rates are the same (“non-differential” assumption). However, it is suspicious that this assumption is valid in many case-control studies. Unfortunately, no test is available so far to test the validity of the assumption of non-differential misclassification when the validation data are not available. We propose the first such method to test the validity of non-differential assumption in a case-control study with 2 × 2 contingency table. First, the Exposure Operating Characteristic curve is defined. Next, two non-parametric methods are applied to test the assumption of non-differential misclassification. Three examples from practical applications are used to illustrate the methods and a comparison is made.