Sialytrisaccharides based on $eta$-galactosyldisaccharides were synthesized using $eta$-galactosidase and trans-sialidase in one pot. Using $eta$-galactosidase from Bacillus Ciculans and trans-sialidase from Trypanosoma cruzi simulaneously, 6mM sialyltrisaccharides composed of about 95% NeuAc$alpha$(2,3)Gal$eta$(1,4)GlcNAc and 5% NeuAc$alpha$(2,3)Gal$eta$(1,6)GlcNAc were produced from a reaction mixture containing 25mM o-nitropheny1-$eta$-D-galsctolneuraminic acid. One beauty of this reaction was that a secondary hydrolysis of the disaccharide intermediate occurring between the activated galactopyranoside and N-acetylgucosamine was prevented. Using $eta$-galactosidase from Escherichia cloi and the same trans-sialidase, 15mM sialyltrisaccharides composed of about 90% NeuAc$alpha$(2,3)Gal$eta$(1,6)GlcNac and 10% NeuAc$alpha$(2,3)Gal$eta$(1,4)GlcNAc were produced from a reaction misture containing 400nM galactose, 800nM N-acetylglucosylation rection between galactose and N-actylgucosamine was diminant since the disaccharide intermediate mainly resulted sreulted in the silylated product.