The workpre sented in this paper is devoted to the evaluation of the dependability of computer control systems in power plants. Two complementary approaches are used to analyze and evaluate the dependability of such systems, based respectively on analytical modeling and experimental validation. Both approaches as well as examples of their mutual interactions are briefly illustrated on a subsystem of a specific computer control system. The analytical approach allows evaluation of dependability measures such as availability and identifies the most influential dependability parameters. Fault injection provides the numerical values of the above mentioned parameters and allows identification of specific behaviors that may not have been considered by the analytical model.