In everyday life, the effect of similarity occurs when there has been attested an identity or a great similarity between two or more persons. Multiple systematic research studies have shown that this effect has a highly important role in creating inter-human affiliations. Interpersonal attraction, sympathy, friendship, love, group solidarity appear and are continuously maintained by this effect. In saying that inter-human affiliations are generated mainly on the criterion of similarity, it is important to keep in mind that there are several types of similarity in practice. It has been observed, for instance, that the physiological/morphological similarity matters very often (height, eye color, shape of hands etc.). There are also many cases where the personological similarity matters (extrovert-introvert, social and affective intelligence etc.). There can also be a cognitive-axiological similarity (beliefs, attitudes, values etc.) and a sociological similarity (social class, religion, race, ethnicity, social status etc.). Despite its popularity, the similarity effect cannot be treated, however, in absolute terms. In this context, it should be firstly noted that the greatest majority of the empirical evidence related to this effect, has been obtained in laboratory conditions, which can generate problems of extrapolation to situations from real life. Secondly, the fact that the resemblance to certain people doesn’t make us happy, but rather upsets us shouldn’t be disregarded. And finally, there are frequent situations where we feel attracted to others by virtue of complementary needs, and not by that of matching personalities, attitudes or religious affiliation. In fact, the effect of similarity conveys an ambivalent phenomenon: depending on the circumstances, it may be a factor of aggregation, but also of disaggregation, edification, and demolition. The destructive nature of the effect in question is fully manifested in the process of education, especially during the didactical evaluation. Many times, there can be observed a tendency of the teacher to project himself/herself as a model, building implicit scales centered on „I”, constantly reducing „the other” to his/her own scale. What should be done to remove the negative influence of the effect of similarity on the education? First of all, it is very important that teachers have a professional training that would prevent them from presenting themselves as models when organizing and conducting the teaching-learning process. Then, it is necessary to reshape the procedure of didactical evaluation in a manner that would reduce to the maximum the subjectivity of the teachers (the use of multiple correcting technique, ensuring anonymity of the written examinations, increasing the number of current evaluations and so on). And finally, thirdly, the formation and development of the students' capacity of auto-evaluation should to be encouraged by all possible means.