Lectin histochemistry was conducted to identify sugar residues of the polyglucosan bodies (PGB) in the feline brain. PGB stained with Concanavalia ensiformis agglutinin (Con A) and peanut agglutinin, but not with soybean agglutinin, wheat germ agglutinin, Dolichos biflorus agglutinin, Ricinus communis agglutinin or Ulex europaeus agglutinin. In addition, PGB bound to Con A after periodate oxidation. These results suggest that feline PGB contain mannose and galactose in addition to glucose and that the partial component of PGB is derived from rough endoplasmic reticulum and the Golgi apparatus.