In a rare earth ferromagnetic metal the effective exchange field (H/sub eff/) impressed on the conduction electrons is in general so large as to inhibit the occurrence of superconductivity in zero external field H. A discussion is presented to point out that in certain ferromagnetic metals H/sub eff/ opposes H and allows conduction electron polarization to be canceled so that, if these metals also possess a predominantly attractive electron-electron interaction, the possibility arises that superconductivity will occur in the compensation region. Since the cancellation will presumably occur for H approximates ,-H/sub eff/, critical fields may be obtained that exceed the limit derived for ordinary superconductors by an order of magnitude. (H.D.R.)