A porcine (1-->3)-alpha-N-acetyl-D-galactosaminyltransferase was obtained in a state suitable for preparative-scale (mg-scale) synthesis using simple procedures requiring only three days of effort. The enzyme thus prepared transferred GalNAc efficiently from UDP-GalNAc to six different chemically synthesized di- and tri-saccharide H-active structures to yield blood-group A-active oligosaccharides that were characterized by 1H NMR spectroscopy and mass spectrometry. This work further demonstrates the efficiency and attractiveness of using glycosyltransferases in a combined chemoenzymatic approach for the rapid production of biologically active oligosaccharides.