Treatment of the fallopian tubes by Ovabloc silicone intratubal polymer (ITP; Dow Corning silastic 382 Medical-Grade Elastomer) is used for permanent female contraception. Studies on animals show minor structural changes in the tubal epithelial lining caused by the ITP and suggest reversibility of tubal integrity after removal of the polymer. The aim of this study was to examine the impact of the ITP on the human tubal epithelial lining. From 13 patients treated with ITP, 23 fallopian tubes were studied by light microscopy and transmission electron microscopy. The examined 19 isthmical and 10 ampullary parts show marked structural changes. In the isthmical parts of the fallopian tubes, cellular and ciliary changes develop immediately after insertion of the silicone polymer. As for the ampullary parts, the cellular and ciliary changes are related to the ITP exposure time. The changes in the isthmus and ampulla are persistent for at least 15 months after removal of the ITP. It is not known whether the effects are reversible.