Early endosomes (EE) provide the starting point for late endosome maturation. The EEs are mainly derived from primary endocytic vesicles that fuse with each other. EEs receive endocytic cargo not only through the clathrin-mediated pathway but several other pathways. In addition to their roles in normal cell physiology, endocytic processes play a key role in many diseases such as Alzheimer disease and inherited lysosomal storage diseases. Traditional methods for isolating endosomes are based on density gradient ultracentrifugation. The protocol requires large amount of starting material and the methods are tedious and time consuming. The Endosome Isolation and Cell Fractionation Kit provides a spin-column based novel endosome isolation technology that is rapid, simple and requires smaller number of cultured cells or milligram amounts of tissues. This kit can precipitate and significantly enrich early endosomes from cultured cells or tissues. The availability of the kit should facilitate the research in the field.