  We consider consequences of local disorder in systems experiencing first
order phase transitions. Such systems can be of rather different nature. For
example, manganates showing gigantic magnetoelectric effect, doped
antiferroelectrics or biomembranes. Monte-Carlo computations performed have
shown that the disorder increases the temperature interval where the high- and
lowtemperature phases coexist and this provides thermodynamics in the
disordered systems distinct from the thermodynamics of classical homogeneous
systems.
