The paper presents conditions for avoidance of branching in the synthesis of 7-R spatial mechanisms. These conditions are based on the theory of linearly dependent screws by Hunt (1978) and on the theory about the existence of tangent loci in the so-called stationary configuration of the mechanisms (Sandor and Zhuang 1984a and b). First, the conditions for stationary configuration are obtained on the basis of the above-mentioned theories. Then, since the related branches are at both sides of the special canfiguration, corresponding conditions for avoidance of branching are obtained. Finally, we present a numerical example of the synthesis of a 7-R spatial motion generator with prescribed finitely separated positions, prescribed crank rotations, and with application of branching defect avoidance.