The paper presents a comparison of the two most commonly used diagnostic tests for orthorexia – ORTO-15 Questionnaire and BOT (Bratman Orthorexia Test) – that use data-mining methods. Orthorexia nervosa is perceived as a new, unclassified eating disorder, which is characterized with pathological fixation on the consumption of healthy foods. In order to assess the coherence of the aforementioned tests, a method from the data-mining group, i.e. correspondence analysis, was used in addition to traditional statistical methods. On the basis of (...) the obtained results, only average correlation between ORTO-15 Questionnaire and BOT test was found. More cases of orthorexia were diagnosed with the use of ORTO-15 Questionnaire, which may result from its higher sensitivity. It was also noted that the coherence of tests increases with increasing BMI values, despite no relationship between BMI and the presence of orthorexia having been proved. Diagnosis of an orthorexia case with the use of BOT test implies that there is a high probability that it will also be diagnosed with the use of ORTO-15 test, but not necessarily the other way around. The performed correspondence analysis confirmed a not very strong coherence of the results of both tests. (shrink)