The principle of equality has traditionally been a topic in public law scholarship. In recent years, however, it is increasingly discussed in private law scholarship. This paper discusses how the principle of equality operates in private law. The conclusions are as follows: First, private law legislation as well as private law interpretation have been undoubtedly bound by the principle of equality. However, private law relationships between private persons are not. In this area, the so-called horizontal effect of principle of equality or rights thereto shall be denied. Second, there are examples in private law where the principle of equality appears to be applied. Resolutions, decisions, or di spositions by or in corporations, associations or long-term contractual relationship can be illegal if they are discriminatory; refusal to deal, suspension of dealings, or refusal of admission to an organization or long-term contractual relationship can be illegal if they are discriminatory; the exercise of ownership rights or the operation of an organization can be i llegal if it has been open to the publi c while excluding certain persons or groups of persons in contradiction to that practice. These are manifestations of the inherent limits of private autonomy, of the principle of good faith and fair dealing, of abuses of rights, and of the general right to personality, however, rather than of the principle of equality, especi ally constitutional equality. Finally, legislators can still impose obligations on private persons to treat other private persons equally, and many do. Given the inherent tension between private autonomy and equality, however, such legislation should be limited to specified traits and/or specified areas and should not be too broad. Relevant legislations in the United States and Germany demonstrate it. It is questionable whether the drafts for the general equal
 treatment act currently being discussed strikes such a balance.