The efficiency of immunotherapy with autovaccines was determined in 162 patients with urinary infections produced by Gramnegative bacteria. In each case quantitative urocultures were performed, with examination of the urinary sediment, and blood samples taken before and after treatment with autovaccines in order to determine the agglutination and hemagglutination titer with autovaccines in order to determine the agglutination and hemagglutination titer with regard to the incriminated germs. The latter were identified by their enzymatic and serologic characters and their sensitivity to chemotherapeutical agents. Autovaccines were prepared (2, 3 or even 4 series), repeating the tests after administration of the vaccines. Following immunotherapy, 87 patients (53.7%) presented repeated negative urocultures, 11 presented alternate positive and negative cultures, and 64 remained positive in spite of the treatment applied. There was an increase in hemagglutination titers in the patients with negative urocultures following autovaccination. To conclude it is assumed that the efficiency of immunotherapy with autovaccines depends upon their administration at the onset of infection after the patient has benefitted by the chemotherapeutical treatment. In the cases in which germs belonging to different taxonomic groups are repeatedly isolated in urocultures, it is recommended to prepare a polyvalent autovaccine to be applied in 2-3 series.