This paper studies the conjugated involute profile which are used in internal gear pumps. In this type of gear mechanisms, the internal gear profile is completely conjugate of the external gear profile. A composite line of action curve is obtained because the root fillets also play role in engagement cycle. The perfomance of the mechanisms is increased. By applying consequent transformations, firstly the tooth surface of the generated external gear is obtained and secondly the tooth surface of the conjugated involute internal tooth surface is obtained. Also asymmetric tooth is considered. Mathematical models of generating and generated tooth surfaces are given. Based on the given mathematical models, a computer program is developed to obtain generating and generated surface. Conventional and conjugated involute profiles are compared.