The present invention relates to a method for preparation of the trisaccharide 6&prime-O-sialyllactose (formula (I)) or salts thereof as well as intermediates in the synthesis and for the use of 6&prime-O-sialyllactose salts in pharmaceutical or nutritional compositions.本発明は、式(I)で示される三糖およびその塩の合成ならびにその合成に用いる新規中間体に関した。