Recent progress in research of crystallization processes of fats and lipids is reviewed with an emphasis on kinetic properties of polymorphic crystallization in pure and mixed systems. It is shown that physical techniques using Synchrotron radiation X-ray beams, differential scanning calorimetry and FT-IR measurement have enabled workers to relate the molecular-level structures and crystallization kinetics of fats and lipids. The influences of crystal seeding and shear stresses on crystallization kinetics are also discussed. The polymorphic crystallization properties thus reviewed are relevant to separation phenomena of natural fat resources.