An active binary XY UMa revisited

New extensive multicolour photoelectric photometry, performed since 1994, i s presented. 17 more-or-less complete light curves were obtained and analyz ed. The Wilson-Devinney code applied to the BVRI light curves without the m aculation effect together with published spectroscopic mass ratio and semi- major axis yielded new absolute parameters of the eclipsing pair: m(1) = 1. 10 M-circle dot, m(2) = 0.66 M-circle dot, R-1 = 1.16 R-circle dot, R-2 = 0 .63 R-circle dot, a = 3.107 R-circle dot and the orbital inclination i = 80 .9 degrees. The observed orbital period changes are conclusively explained by the mutual action of the third body in the system (P-3 = 30 years) and t he maculation effects. Simultaneous analysis of the period changes and the visual brightness excludes the possibility of their explanation by Applegat e's mechanism. The differences in the maxima heights caused by the maculati on exhibit variations with the period of 709 +/- 10 days. The distance to t he system d = 86 +/- 5 pc determined from the absolute dimensions and lumin osities of the components is larger than the Hipparcos astrometric value d = 66 +/- 6 pc.