Helicobacter pylori infection is twice as frequent in blacks as in whites. It has been postulated that the apparent increase in susceptibility to H. pylori infection in blacks might have a genetic basis. A case-control seroepidemiologic study of H. pylori prevalence was performed in 108 healthy Hispanic volunteers. Eighty-nine Hispanics were matched (1:1:1) with blacks and whites for age and socioeconomic status. There was an inverse correlation between H. pylori infection and educational level that remained after logistic regression analysis adjusting for age and sex. The adjusted prevalence of H. pylori infection was almost identical in Hispanics and blacks and significantly higher than in whites. Because Hispanics do not constitute a race, the increased prevalence of H. pylori in Hispanics and blacks is unlikely to be genetic. It is speculated that the unrecognized bias is a reflection of a generation cohort phenomenon related to the generational distance from very low socioeconomic status, i.e., the prevalence of H. pylori in Hispanics and blacks is currently lower than that of their parents but higher than that of the white population, which has experienced higher socioeconomic status for several generations.