The authors studied the seroprevalence of Helicobacter pylori infection and the risk factors for infection, among adult volunteers from Szabolcs-Szatmár-Bereg county, East Hungary in year 2000. Sera were collected from 756 adults (328 males, 428 females, m/f = 1.5:2; mean age 42.4 yrs.; range 18-69 yrs.). Anti-Helicobacter pylori IgG and anti-CagA IgG antibodies were identified serologically using a sensitive ELISA technique. A questionnaire was completed to obtain necessary informations. The overall rate of seropositivity was 58.6% (45.2% in those aged 18-29 and 69.6% in those aged 50-59). Seropositivity was significantly higher in rural population than in urban area (p < 0.001), sharing a bed (p < 0.001), if parents were manual workers (p < 0.001), between keepers of cat (p < 0.005). The authors found a significant inverse correlation between Helicobacter pylori infection and educational level (p < 0.001), income (p < 0.005), absence of water supply and sanitation (childhood: p < 0.001, adulthood: p < 0.05). There were no significant differences in Helicobacter pylori infection related to gender, subject's occupation, smoking and drinking habits, gastric symptoms, family history of ulcer or gastric cancer. 67.5% of Helicobacter pylori positives were anti-CagA positives too. Helicobacter pylori positivity is higher than in developed countries, and than in the more developed county Vas.