Lactoferrin, which binds iron very tightly but reversibly and is a useful protein because of its various biological functions, was purified from defatted milk by use of an expanded-bed column with Streamline SP as adsorbent. Adsorption of lactoferrin in defatted milk is found to obey a Langmuir isotherm. The isotherm is also obeyed in phosphate buffer, and the amount of lactoferrin adsorbed decreased rapidly with an increase of NaCl in the buffer. With the expanded-bed column nearly 90% of lactoferrin in the applied milk is recovered with purity of ca. 90% through high apparent velocity of ca. 150 cm/h in the bed.