Microcrystalline cellulose with the mean diameter of around 3 &mgr;m inD2Oaqueous suspension was investigated by a ultar small-angle neutron scattering method. The ultar small-angle neutron scattering revealed that the fractal-like structure of the microcrystalline cellulose particle has maintained in the region from6×10−3up to1.0×101&hthinsp;&mgr;m.It means that the microcrystalline cellulose particles aggregate in the aqueous suspension since the maximum size is larger than that of the microcrystalline cellulose particle. In addition, it is also supposed that the aggregated substance keeps the fractal structure. ©2000 American Institute of Physics.