Giant cells induced in roots of I. balsamina by Meloidogyne javanica and M. incognita were examined by EM and light microscopy. The 1st sign of giant-cell formation was division of cells surrounding a larva. Cell plate alignment apparently proceeded normally, but cytokinesis was unsuccessful, and binucleate cells formed subsequently. No wall breakdown was evident then or later. The number of nuclei apparently increased by repeated mitosis without separation by cytokinesis. Although no holes in walls were observed, wall stubs were found, and mechanisms for their formation are suggested.