This paper analyzes the emergence and practice of company groups as well as other legal institutions aimed at protecting creditors and minority shareholders of controlled companies in Polish law. To avoid misunderstandings, the concept of groups of companies is defined as an association of two or more companies dominated by a single entity (dominant firm). In principle, it is assumed that such groups of companies consist of companies possessing independent legal personality. However, participation of other legal entities in the group should also be considered. In particular, the classical narrow definition of a group of companies, if adopted by a given statute for the purpose of protecting creditors or minority shareholders, makes the task of circumventing the law rather easy. Thus, it should be sufficient if a group is dominated by a partnership or a cooperative organization. For similar reasons, a requirement that a “group” shall consist of at least three companies seems to be too formalistic and imperfect. Hence, the definition of a “group” or “dominance” may be given different meanings for various purposes. In this paper the notion of “dominance” is patterned after the seventh EU Directive, unless defined otherwise.