Calcium plays an important role in many physiological processes, especially in fruit softening. The low calcium content in fruits causcs their rapid softening. The role of calcium in fruit softening is complex. Apoplastic calcium strongly affects the function of plant cell walls and membranes. Cell walls are the structures where the main role of calcium is cross-linking with pectin which increases cell cohesiveness. Calcium ions maintain also membrane selectivity. In the symplast ²⁺ ions alone or in complex with calmodulin influence a lot of metabolical processes which change the rate of fruit softening. However, the role of Ca-calmudulin complex in fruit softening is not sufficiently understood.