Re-programmable antifuses and structures utilizing re-programmable antifuses are presented. Such structures include a configurable interconnect circuit having at least one re-programmable antifuse, wherein the at least one re-programmable antifuse is configured to be programmed to conduct by applying a first voltage across it and is configured to be re-programmed not to conduct by applying second voltage across it, wherein the second voltage is higher than the first voltage. Other embodiments of antifuses include an initializing step prior to programming.