To analyze the interaction between normal human placentas with Trypanosoma cruzi, optical and electron microscopy of chorionic villi stroma cocultured in vitro with 1.5 x 106 Tulahuen strain Trypomastigotes of the T. cruzi for 1 h, 3 hs and 12 hs in Eagle minimal essential medium were done. An agglutination of chorionic villi in experimental cultures (with T. cruzi) from 1 h cultures was observed that was not present in control ones. this phenomenon resisted soft mechanical agitation to separate the isolated villi. Microscopical observations of stromal villi showed edema, separated structures and increment of Hofbauer cells as found by qualitative analysis. The chorionic villi agglutination could be caused by glycoproteins' modifications of the trophoblast, which in turn could be caused by secreted products of T. cruzi, as other authors have postulated in various cells' types. The increment of Hofbauer cells could represent a regulator mechanism of the placenta to equilibrate the intracellular water of the villi stroma.