A relay set (4, 4') for the optical system of a rigid endoscope, the optical system including an objective (1) at the distal end, an ocular (5) at the proximal end and between them a relay lens system consisting of several relay sets (2, 3, 4), the relay set (4, 4') consisting of two half sets (4.1, 4.2) having the same lens units (11.1, 12.1, 13.1; 11.2, 12.2 13.2) arranged symmetrically with respect to the center (10) of the set (4, 4'), each half set (4.1, 4.2) consisting of two positive power lens units (11.1, 13.1; 11.2, 13.2) at the ends and one negative power lens unit (12.1; 12.2) in the middle, is characterized in that each half set is of Triplet design.