It has been established that the meander asymmetry in plan may be quantitatively assessed using the meander's apex deviation from the axis of symmetry and unequality of the angles of entry and exit. The contributions of the two factors to the meander asymmetry are abount the same. An index of asymmetry is introduced - AFt, which takes into account both factors, and another index - AF: which approximates regularities of AF: changes. The two indices may be applied both to describe meanders' pattern, along with other morphometric characteristics, and to investigate into importance of asymmetry in the meander evolution.