The article is concerned with basic issues connected with the role of custom in employment relations, with a particular emphasis on judicial jurisprudence and the method established therein to use the custom in relation to statutory law. This has a primary importance in view of the fact that custom penetrates the system mainly through court rulings, also in the system of civil law and not only the case law. The conclusions reached indicate that custom may occur both in the provisions of an employment relation, as an addition to mutual rights and obligations of the parties to that relation and sometimes constitutes an inherent element of the manner in which work is performed. Moreover, it seems that, in certain cases, the custom, being in the first place a determinant of the manner in which work is performed, with time becomes an element of the provisions of the employment relation, thereby shaping the mutual rights and obligations of the parties. In order for that to occur, a given custom must be, at least passively, known and accepted by both parties to an employment relationship.