We have tried to verify, in some experiments, the silver oligodynamic action upon the lymphocytic choriomeningitis virus, WE strain the poliomyelitis virus, MEF1 strain, and the vaccinia virus, Instituto Oswaldo Cruz strain, as we have done with the influenza virus, PR8 strain and DL/Rio strain. In the tests we used clay pitchers covered in the inner surface with a thin layer of silver of with powdered silver mixed with the clay material. The 10 per cent infectious cerebral emulsion of the lymphocytic choriomeningitis virus or of the poliomyelitis virus were put into the pitcher and the pathogenic power for mice verified, at regular intervals, by the intracerebral injection of 0,03 ml. The results expressed in the tables 1 and 2 indicates that those viruses resist the silver oligodynamic action. In the case of the vaccinia virus, the dilution was put into the pitcher in the same way. The virus presented, too, complete resistence, as we can see in the figures 1, 2 and 3. Control experiments made with Micrococcus pyogenes and Escherichia coli, put into the pitchers with silver, showed that the bacteriae were dead after 20 hours. As we emphasized in the paper about the influenza viruses, the reported phenomenon is important because we know that the oligodynamic effect is observed upon microorganisms like bacteria, protozoa and other living beeings altering its properties or killing them and, therefore, intersting from the biological point of view. The phenomenon can also be applied to the isolation of viruses with bacterial contamination.