Recent clinical and experimental studies indicate that the pathogenesis of a septic process in critically ill patients may be divided into two stages: (1) a systemic inflammatory reaction and (2) immune paralysis. Verification of biological markers of both stages is the key point for choosing adequate drug therapy. Immune paralysis virtually shows no clinical symptoms, at the same time this condition can be diagnosed at the earliest stages, by applying a number of laboratory techniques. For the time being, the determination of the level of IL-10 and TNF-alpha and their ratio in the serum are most suitable for this purpose in routine practice. The estimation of the levels of mHLA-DR expression and apoptotic markers of different cell populations is of unquestionable practical value. The diagnosis of immune paralysis requires urgent pathogenetically substantiated therapy. Despite the fact that clear criteria for mediator-controlled therapy have not been defined so far, it is absolutely clear that it is precisely such an approach that is most justified and promising. Furthermore, immunological parameters in the use of new therapy options need meticulous monitoring for the evaluation of the efficiency and adequacy of drug action. All the issues in question--from diagnosis to criteria for the adequacy of therapy--require further development and they will be undoubtedly to have the most direct impact on the results of treatment in intensive care unit patients.