Cupric and ferric ions were able to inactivate five enveloped or nonenveloped, single- or double-stranded DNA or RNA viruses. The virucidal effect of these metals was enhanced by the addition of peroxide, particularly for copper(II). Under the conditions of our test, mixtures of copper(II) ions and peroxide were more efficient than glutaraldehyde in inactivating phi X174, T7, phi 6, Junin, and herpes simplex viruses. The substances described here should be able to inactivate most, if not all, viruses that have been found contaminating medical devices.