A set of extensive long-term photometric observations of the symbiotic star YY Her covering the period of (JD 2 451 823 - 2 453 880) is presented. We explain the periodic variations of the brightness of YY Her by the eclipses of the components in the symbiotic system. A model with a deformed (non-homogeneous) envelope, surrounding the white dwarf is discussed. The open question is the nature of the envelope - is it a spherical envelope, torus or thick accretion disk?