To assess the seroprevalence of Helicobacter pylori (HP) in children with insulin dependent diabetes mellitus, a serological test for Helicobacter pylori (anti-HP IgG with ELISA) was performed in 88 diabetic and 42 healthy control children. Anti-HP IgG was positive in 49/88 (55.6%) of diabetics and 13/42 (30.9%) of controls (p<0.01). Diabetic children were divided into two groups according to HP status: HP(+) and HP(-). The two groups were compared for age, gender, duration of diabetes, diabetic control (HbA(1c)), SDS for height and gastric emptying time. Seroprevalence of HP was higher in IDDM patients than in healthy controls. Duration of diabetes was the only factor which correlated significantly with HP status. HP status was not related to gastric emptying time.