The purpose of this study uas to determine whether Helicobacter pylori infection can contribute to growth deficit, especially in pubescent children who need large amounts of iron for growth. A structured questionnaire writs sent to the parents of 532 healthy children aged 10 to If years (mean 12.9) to obtain demographic information on the parents and the environment. Of the 532 questionnaires sent out, 375 (70.5%; 170 girls and 205 boys) were returned. After collecting blood samples from participants, haemoglobin, serum iron, total iron binding capacity, serum ferritin, and serum IgG antibodies to hi pylori were measured. The effects of risk factors such as If pylori infection, iron deficiency anaemia, sex, socioeconomic status, type of house, and crowding index on growth were analysed using multiple regression analysis. Of 63 H pylori positive children, 18 (28.6%) were below the 25th centile Values for height, compared with 63 Elf 312 (20.2%) H pylori negative children. The prevalence of H pylori infection was 15.5% (53 of 343) in children without iron deficiency anaemia and 31.3% (10 of 32) in those affected. The relative risk of short stature was 2.2 (95% confidence interval (CI), 1.0 to 4.8) for iron deficiency anaemia, and 1.4 (95% CI, 0.8 to 2.4) for H pylori infection. The mean height was significantly Bower in the group having both hi pylori infection and iron deficiency anaemia. Therefore, hi pylori infection accompanied by iron deficiency anaemia, rather than H pylori infection per se, might delay pubertal growth.