Colonization by Helicobacter pylori (HP) in 53 patients after remote gastric surgery and Roux-en-Y anastomosis was investigated using a rapid urease test (CU-Test) and histology (H&E and Giemsa stain). The pH-value of gastric juice was measured. HP infection of the gastric remnant was found in 56% of 43 patients after partial resection and in no case after total gastric resection. HP-positive and HP-negative patients were comparable in age, sex distribution, indication and technique of gastric operation (except for total gastrectomy with jejunal gastric replacement), intake of acid inhibiting drugs and antibiotics was well as in the presence or absence of a macroscopically visible pathology of the gastric mucosa. On the other hand, the two groups differed in their histological findings, pH-value of gastric juice and time interval since surgery. HP infection of gastric remnants is associated with significant glandular atrophy and an additional rise in gastric intraluminal pH compared with HP-negative patients. Both changes may involve an increased risk for gastric cancer. In this report on patients with Y-en-Roux operation there is no decrease in gastric HP-colonization with an increasing interval since the time of operation, but rather an increase. This phenomenon seems to depend on the absence of enterogastric reflux.