This study was conducted on 112 children with congenital heart disease (CHD) [53 cyanotic & 59 acyanotic] 59 asthmatics and 100 normal controls. They were selected over a period of 8 months from 1/2/1999 to 1/10/1999. All infants and children studied were 6 to 36 months of age. The aim of the study was to estimate the seroprevelance of H. pylori in children with CHD and comparing them to another group of sick children like asthmatics then versus normal controls. The 100 normal controls showed 18% sero-positiveness for H.pylori. 32.1% of the cyanotic group was sero¬positive compared to 18.6% of the acyanotics. Asthmatics scored 35.6 %. There was a highly positive correlation between age and H. pylori infection. Incidence of infection was not affected by mother education or residence (rural vs. urban). We concluded that H. pylori infection showed high incidence in chronically ill children. It has to be considered as a risk for development of ulcer disease in CHD especially that these children may eventually undergo surgery, which is another risk factor for peptic ulcers. It is also commonly encountered in asthmatic children. Further studies on those two groups of patients are needed.