This paper entitled "Optimization of the synthesis of a 6-bar Stephenson I mechanism for a knee prosthesis using genetic algorithms and Matlab grip", was developed using the method of genetic algorithms to design of articulated four bar mechanisms applied to this system of six bars. To optimize the mechanism five corresponding prescribed positions defined five positions of the femur, of these positions ten points precision five belonging to the mechanism 1, and five belonging to the mechanism 2. Stephenson I, mechanism was taken as the composition of two mechanisms articulated four separate bars each other, thus applying the programming code optimization synthesis by genetic algorithms for four-bar linkage developed in Matlab, each; with a randomly created population, based on the domain of each variable (length of the links and angle of movement) of eight thousand individuals, and encod...