In the goblet cells in the caecum of control rabbits only sialo- and sulphomucins were produced and the same glycoproteins were in the brush border of the surface epithelium. By enterotoxaemia there was a mixture of both acid and neutral glycids or mixed ones in some goblet cells. In lumina of the crypts and on surface of the mucosa, the neutral mucins were predominantly present. By enterotoxaemia binding of soybean agglutinin (SBA) and Ricinus communis agglutinin I (RCA I) in the brush border and in the Golgi apparatus was diminished or abolished. The binding of wheat germ agglutinin (WGA) was reduced to some goblet cells or surface of the crypts. Binding of concanavalin agglutinin (ConA) was not changed in comparison with control rabbits. These results showed that enterotoxaemia in rabbits is related, among other things, also to changes in mucosal glycid composition, binding of SBA and RCA I lectins and these changes precede morphologically apparent alteration.