Abstract: The structure of the organic matrix of rat enamel was studied with the aid of scanning electron microscope (SEM) utilizing a replica technique. Samples of rat enamel were first deorganified with hydrazine and then impregnated with a low viscosity resin. These were then sectioned, longitudinally or transversely, polished and demineralized with either 0.1 or 0.5M EDTA (Ethylene diamine tetra acetic acid) for 12, 24 or 48 hours. Longitudinal sections were treated with 0.1M EDTA for short periods of time showed a non-fibrous layer, along the dentino-enamel junction, which was covered with small holes. When a 0.5M solution of EDTA was used, this non-fibrous sheet was completely etched away. The major portion of the organic could now be seen along the rod sheath. Demineralization of the sample left many small voids within the gel, where crystallites once were present, thus giving the organic matrix a fibrillous appearance. Transverse section, treated with 0.5M EDTA showed no evidence of any structures. When these sections were treated with 0.1M EDTA the organic material could be seen predominantly along the rod sheath. Large globules of organic, covered with small indentations, could be seen in areas which had no rods. Smaller globules, covered with holes, could be noticed along the tops of some of the arcades.