In complex automated equipment, mechatronic and robotised systems, maintenance and corresponding diagnostics have extreme significance, because failure may cause considerable damages to the manufacturer. In the lecture we will deal with maintenance of robotised systems. First we will describe properties, introduction of maintenance demand of these technical systems. We will discover properties of maintenance strategy of robot systems. In the presentation we will show a method connected with cost analysis, which will serve as a basis for effective introduction of possible maintenance technology.