H. pylori infection can be diagnosed serologically. We evaluated an ELISA kit (Helicobacter pylori IgG, DIESSE) prepared using a glycine extract of an autoctonous H. pylori strain which produced the highest biologically active urease titre out of five strains tested. The kit was tested with serum samples from H. pylori-infected and uninfected adults and children. The Western Blot technique was used as reference method for the H. pylori infective status. Based on the results obtained by immunoblotting with serum samples from H. pylori negative subjects, two different cut-off values were considered for adults and children. Sensitivity and specificity were respectively 95% and 100% for adults, 95.6% and 97.8% for children. In conclusion, the clinical accuracy of this commercially available ELISA kit proved to be very good; the adoption of two different cut-off values for adults and children also improved its parameters of reliability.