AbstractFour‐bar mechanisms are widely used in different devices as leading mechanisms that have to provide desired and often complicate motion and sustain substantial forces, accelerations and jerks. As the four‐bar mechanism seems to be a simple device, it is well known that dimensional synthesis is an exacting piece of work. One has to determine the proportions of link lengths needed to accomplish the specified motion and force transformation. Paper discusses optimal synthesis of four‐bar mechanism. The objective of this approach is to determine the optimal values of the mechanism link lenghts, to minimize the difference between the trajectory “T” of the arbitrary point C on the mechanism coupler link and prescribed trajectory “P”, while hinge forces have to remain within the prescribed values.