One hundred and thirty-nine subjects representing a randomly selected sample of an Estonian urban population examined endoscopically, bioptically and bacteriologically in 1979 was re-examined in 1985. In the antrum the development of superficial gastritis was clearly associated with the appearance or persistence of Helicobacter pylori (HP) infestation. The further progression of superficial gastritis could less clearly be related to HP infestation, although regression and progression of antral superficial gastritis was significantly associated with the disappearance or presence of the bacteria. The progression of atrophic antral gastritis as well as the development and progression of all body gastritis seemed unrelated to the HP infestation. It is concluded, that HP infestation is in some way involved in the appearance of the first stages of chronic gastritis, but is less related or unrelated to its further progression, which is probably determined mainly by factors other than HP.