The basic aim of the paper is to present the theory of tacit knowledge as a basic research area for innovation. The first part presents the origin of the theory and its main components. The semiotic aspects of this theory will also be treated here. The second part highlights the role of tacit knowledge in innovation processes. It also describes the practical efforts of enterprises already made for the utilization of several forms of this knowledge. The third part of the paper expounds the semiotic approach to innovation processes, as it is based on the theory of tacit knowledge. In the center of this explanation, the semiotic interpretation and transformation of tacit knowledge stand as a special form of knowledge considered as highly important in the preparation of new ideas.