Reasons for laboratory misdiagnosis that is observed in general health care network (GHCN) and penitentiaries were studied. The clinical efficiency of the diagnosis of tuberculosis in the GHCN by the Ziehl-Neelsen method is largely determined by three major factors, each of which is fundamentally important in assessing the result. The first factor is the adequacy of making up a cohort of patients having the symptoms of productive cough in the course of 2-3 weeks or more who are to be examined for tuberculosis by laboratory studies. The second is the quality of a diagnostic material. The third is the quality of laboratory specialists' work. The paper shows it necessary to implement programs for the internal control and external assessment of the quality of laboratory studies and to optimize (centralize) the activities of laboratories under the conditions of a regional network.