Pneumococcal vaccine Pneumo-23, used for specific prophylaxis of pneumonia and other pneumococcal infections, was tested in military training units of the North Western, Central and Far Eastern Military Districts. The vaccine used for immunization of servicemen, was shown to have high immunogenicity with no adverse reactions. In the training group of the North Western Military District the epidemiological effectiveness of the vaccine was particularly high a month after immunization and amounted to 83.7%. During the period between month 2 and month 5 after immunization pneumonia morbidity among the immunized servicemen was 6.12 times lower than among the non-immunized ones. In the training units of the Central and Far Eastern Military Districts, where the period of the formation of postvaccinal immunity coincided with the peak of the outbreak of pneumonia, the protective properties of the used batches of the vaccine could be observed as early as during the first month after immunization, which made it possible to recommend this vaccine for urgent prophylaxis in the foci of pneumococcal infection. During the period of 5 months the effectiveness of the vaccine with respect to pneumonia was 62.1-66.2% for all three districts. The effectiveness of the combined immunization of conscripts with vaccines Pneumo-23 and Vaxigrip with respect to pneumonia was higher (78.54%) and the index of effectiveness (4.66) was 1.58 fold greater than in monoimmunization (2.95). The epidemiological effectiveness of the pneumococcal vaccine was high also with respect to other pneumococcal infections: acute bronchitis, acute respiratory diseases of pneumococcal etiology, cases of acute sinusitis and acute otitis. The use of the vaccine for the immunization of servicemen yielded the economic effect equal to 92 US dollars per person.