In some experiments we tried to verify the silver oligodynamic action upon the influenza vírus, A type, PR8 strain and A-prime, DL Rio strain. In the tests we used clay pitchers covered in the inside parte with a thin layer of silver or with powdered silver mixed into the clay material. The infected allantoic fluid was put into the pitcher and the pathogenic power for mice and the hemagglutination reaction verified at regular intervals. The results expressed in the tables indicated that no alterations were presented by the virus in comparison with the controls. Experiments made with Micrococcus pyogenes and Excherichia coli died in 24 to 48 hours. The reported phenomenon is important because we know that the oligodynamic effect is observed upon microorganisms like bacteria, protozoa and other living beings. The alive or dead bacteria didn't alter the referred properties of the virus. We are stil investigating the phenomenon with other viruses and, now, we emphasize that it can be applied for the isolation of viruses as we verified for the influenza virus. This will be one of their practical applications. We think that many others, from the biologic point of view, may arise based on our first observation here presented.