The RS CVn binary XY UMa as a member of a triple system

New minima of the short period RS CVn binary system XY UMa taken in 1997-98 follow the light-time orbit with a 30.5 years period. An inferior conjunct ion of the third body with mass 0.23 +/- 0.03 M. occurred in 1979. It is su ggested that the light-curves of XY UMa taken in 1978-79 were affected by t he eclipse of the binary system by a dusty envelope of the protostellar obj ect responsible also for the observed infrared excess. There is no correlat ion between the long-term brightness variations of the system and the minim a times in the O-C diagram, so its explanation by the Applegate mechanism p roposed recently by Erdem & Gudur (1998) is brought into question.