This article aims to examine the logic subject of the elective syllogisms and attract attention to preparatory books of ÖSS which made fallacious in that subject. The elective syollogisms consist hypothetical and disjunctive syllogisms. In the hypothetical syllogisms exist four forms, two valid and two invalid. In the disjunctive syllogism, validity and invalidity changes according to the structures and the copulas of disjunctive premises. While the disjunctive syllogisms consructioned with some disjunctive premises are valid in the four forms, some other is not valid whole forms. In the high school logic books are clarified to the forms of valid and invalid of the hypothetical syllogisms and showed only the valid forms of the disjunctive syllogisms. In the preparatory books of ÖSS two kind of the syllogisms aren’t distinguished as valid and invalid and examples are given to be accepting entire forms as valid