The purpose of this paper is psychometric and psychological analysis of guessing on entrance examinations, and especially evaluation of classical procedure for reducing guessing which has been used at Department of psychology in Novi Sad, which consisted of instruction against guessing and correction with Abbott formula. As first, we have tried to estimate guessing in several ways, according to classical test theory and item response theory. Besides of analysis of association between different indicators of guessing, we have performed a special form of criterion analysis, by correlating possible indicators of guessing with several personality traits. Basic conclusion of this paper is that guessing is not consistent behavior and because of this it is very hard to measure and eliminate it. The next conclusion is that the applied classical procedure has not been able to eliminate guessing, and that it probably disfavored several candidates.