Abstract: A process for preparing polyvalent, physiologically degradable carbohydrate-containing polymers by enzymatic glycosylation reactions is described. The carbohydrate-containing polymers thus prepared may be used for preparing carbohydrate building blocks. The polyvalent carbohydrate-containing polymers of the invention cause no intolerance reactions in vivo, either in their intact form or in the form of degradation products. The carbohydrate side chain of the carbohydrate-containing polymer is assembled by enzymatic glycosylation reactions in homogeneous aqueous buffer systems directly on a biodegradable polymer. The yields of the glycosylation reaction are significantly improved over known processes, and are often quantitative. This also provides a significant increase in the loading densities. A process for preparing free oligosaccharides by means of the carbohydrate-containing polymers of the invention is also described.