A glycosulfatase activity toward sulfated gastric mucus glycoprotein was identified in the extracellular material elaborated by H. pylori, a bacteria implicated in the etiology of gastric disease. Upon acetone precipitation, an active enzyme fraction at 64% acetone was obtained which on SDS-PAGE gave a major 30kDa protein band. The H. pylori glycosulfatase exhibited maximum activity (314.8 pmol/mg protein/h) at pH 5.7 in the presence of Triton X-100 and CaCl2, and was capable of removal of the sulfate ester groups situated at C-6 of N-acetylglucosamine, galactose and glucose. However, the enzyme was ineffective toward galactosylceramide and lactosylceramide sulfates which contain the sulfate ester group on C-3 of galactose. The results suggest that H. pylori is capable of overcoming the interference by sulfated mucus glycoprotein with its colonization of gastric mucosa.