The influence of Ru substitution on magnetic properties of Y2Fe17 and Y2Co17 (hexagonal crystal structure) is studied via the magnetization measurements performed on single crystals. With the increase of Ru content, the ferromagnetism in Y2Fe17-xRux is suppressed rapidly, and the compounds become antiferromagnetic with characteristic metamagnetic behavior in applied magnetic field. If the ferromagnetism of Y2Fe17 is first enhanced by substitutions of Si and Co for Fe or by interstitial introduction of hydrogen, Ru doping does not lead to an antiferromagnetism but only reduces the Curie temperature of the ferromagnets. In the Y2Co17-xRux system, only a monotonous decrease of all magnetic characteristics occurs without any qualitative changes. All the compounds studied exhibit easy-plane magnetic anisotropy.