Background: Current antibiotic treatment for Helicobacter pylori infection is often associated with frequent adverse effects and resistance to antibiotics. Alternative treatment methods to control H. pylori infection are needed. Some specific strains of lactic acid bacteria (probiotics) in dairy products are known to inhibit the growth of H. pylori in vitro. A clinical trial was conducted to see the efficacy of a specially designed yogurt product containing specific probiotics on the eradication of H.pylori. Method: The yogurt was prepared using three Lactobacillus spp. (L. acidophilus and L. casei) and one commercial starter culture (L. acidophilus, L. bulgaricus and Streptococcus thermophilus). All these cultures were previously evaluated, and found to have strong in vitro inhibitory effects on the growth of H. pylori. Twenty-seven asymptomatic women positive for H. pylori on gastric biopsy and 13C urea breath test were recruited, and administered 175 ml of the yogurt three times a day for 30 days. The 13C urea breath test was administered again, one month after stopping the yogurt treatment to detect the presence of H. pylori.Results: In 26 of 27 subjects, the urea breath test values remained positive, indicating that the consumption of the yogurt had no effect on the eradication of H. pylori. Conclusion: Although the designed fermented milk containing lactobacilli is very effective in the inhibition of H. pylori growth in vitro, eradication of this infection in humans is difficult to achieve by consuming this product.