The present study aimed to evaluate the clinical significanceof the helicobacter pylori stool antigen test compared toother invasive tests (histopathology and rapid urease test)in the diagnosis of Helicobacter pylori infection and to evaluate its sensitivityand specificity in monitoring the H.pylori status before and after eradicationtherapy. H.pylori is an important cause of upper gastrointestinal discomfort inthe Egyptian population. The prevalence of H.pylori infection in the presentwork was 87.74 %. This study was performed on 106 patients suffering from uppergastrointestinal symptoms. They were 57 males and 49 females. Their agesranged from 18 - 65 years with a mean age of 40.47 ± 1.2 years.The included patients were randomly assigned to one of two differentregimens. Regimen A (OAC) which compromised Omeprazole, Amoxicillinand Clarithromycin, while regimen B (OAM) compromised Omeprazole,Amoxicillin and Metronidazole. The difference between the cure rates of tworegimens for eradication of H.pylori was assessed.Both regimens showed low eradication rate, however, on using regimenOAC, the eradication rate showed better response compared to OAMregimen. The overall cure rate of H.pylori was 48.68 %; it was 53.85 % whenusing regimen OAC and 43.24 % with OAM regimen.Helicobacter pylori stool antigen test was proved to be sensitive andspecific in the diagnosis of H.pylori infection especially before eradicationtherapy. It can add to the diagnosis of H.pylori, but still histopathology is thegold standard. It was found that the overall sensitivity of HpSA test beforeeradication therapy was 89.25 % and was 53.85 % after eradication therapy.While the overall specificity before eradication was 92.31 % and 94.59 %after eradication. Treatment of patients with gastroduodenitis showed an overall curerate of 52%, it was 51.86 % in patients who received OAC regimen and 48 % inthose who received OAM regimen. The sensitivity of HpSA test was 88.89 %before therapy and 50 % after therapy. The specificity of the test was 100 %before therapy and 92.31 % after therapy. Patients with peptic ulcer disease showed an overall cure rate of 41.67 %, it was 42.11 % when using regimen OAC regimen and 41.18 % whenusing OAM regimen. The sensitivity of the HpSA test was 92.86 % beforetherapy and 42.86 % after therapy. The specificity of the test was 100 % beforetherapy and 93.33 % after therapy. In patients with gastro esophageal reflux disease, the overall cure rate was 48.72 %, it was 57.89 % when using OAC regimen and was 40 % whenOAM regimen. Gastro esophageal reflux disease may develop aftereradication therapy especially if there is hiatus hernia. The sensitivity of theHpSA test before eradication therapy was 86.54 % and 60 % after treatment.The specificity of the test was 100 % before treatment and 89.47 % aftertherapy. Treatment of patients with non-ulcer dyspepsia showed markedimprovement of their complaints in contrast to previous reports on treatmentof patients with NUD. In patients with non-ulcer dyspepsia, the overall curerate of H.pylori was 46.15 %, it was 57.14 % when using OAC regimen and33.33 % when using OAM regimen. The sensitivity of HpSA test beforeeradication therapy was 92.86 % and 42.86 % after treatment. The specificity ofthe test was 100 % both before and after eradication therapy.Treatment of patients with congestive gastropathy with or withoutoesophageal varices showed improvement of their dyspepsiasymptomatology. In those patients, the overall cure rate was 44.44 %; it was 60% when OAC regimen was given and 25 % when OAM regimen was given. Itis noticed that there was a statistically significant difference between theefficacy of the two regimens in patients with congestive gastropathy. Thesensitivity of HpSA test was 91.67 % before eradication therapy and 80 % aftereradication therapy. The specificity of the HpSA test was 100 % both beforeand after eradication therapy.