Background/aims: Triple therapy with a proton pump inhibitor, amoxicillin and clarithromycin in Helicobacter pylori eradication is widely accepted, but this combination fails in a considerable number of cases. Our aim was to evaluate whether probiotic-containing yogurt affects the success of eradication. The second aim was to investigate the efficacy of probiotics in the prevention of the side effects related to eradication therapy. Methods: A total of 76 histopathologically proven H. pylori-positive patients enrolled in this study were randomized into two groups. The following regimens were recommended: Group A: pantoprazole (40 mg, b.i.d.), amoxicillin (1000 mg b.i.d.), clarithromycin (500 mg b.i.d.), and 125 ml of probiotic-containing yogurt (Bifidobacterium DN-173 010-1010 cfu/g) before breakfast for 14 days; and Group B: pantoprazole (40 mg, b.i.d.), amoxicillin (1000 mg b.i.d.) and clarithromycin (500 mg b.i.d.) for 14 days. Subjects were asked to report any side effects of therapy during the treatment period. H. pylori status was rechecked four weeks after the completion of the eradication therapy by 13Curea breath test. Results: H. pylori eradication was achieved in 25 of the 38 patients in Group A (66%) and in 20 of the 38 patients (53%) in Group B. Although the success rate was higher in Group A than in Group B, the difference was not significant (p=0.350). The addition of probiotics to the triple therapy significantly lessened the frequency of stomatitis and constipation (p=0.037 and p=0.046, respectively). Conclusions: The addition of probiotic-containing yogurt to the triple therapy did not increase the H. pylori eradication rates for the evaluated dosage and model; however, it decreased the frequency of stomatitis and constipation.