Unexpectedly high early reinfection rates are reported in duodenal ulcer patients in whom Helicobacter pylori infection had been considered eradicated two months (T2) after appropriate therapy. Since some of these re-conversions to Helicobacter pylori positivity were probably recrudescences of a latent infection rather than reinfections, studies were performed to evaluate whether the type of antral gastritis could predict the infection outcome. In 142 eradicated patients at T2, endoscopies were repeated 6 (T6), 12 (T12) and 24 (T24) months after therapy to assess Hp status and to score antral gastritis. Re-conversion to Hp positivity occurred in 14.79% between T2/T6, in 5.40% between T6/T12 and 11.11% between T12/T24. The absence of active antral gastritis at T2 with its 87.31% negative predictive value was a fairly good marker of subsequently confirmed eradication (p = 0.017). It is suggested that, evaluation of antral gastritis soon after an eradicating course, could be a reliable parameter in assessing "true" Hp eradication.