Objective: Standard triple therapy for Helicobacter pylori has a low eradication rate in Turkey. The aim of this study was to evaluate and compare the effectiveness of 7-day and 14-day lansoprazole, amoxicillin, clarithromycin, and bismuth subsalicylate (LACB) treatment regimens as first-line H. pylori eradication therapies. Materials and Methods: This study included 70 patients with symptoms of dyspepsia and a positive H. pylori stool antigen test (SAT). Thirty-five patients received the modified quadruple therapy regimen for 7 days (LACB-7) whereas the remaining 35 patients received the treatment for 14 days (LACB-14). Eradication was assessed by SAT 1 month after the end of therapy. Results: A total of 64 patients completed the therapy. The cumulative per-protocol (PP) and intention-to-treat (ITT) eradication rates were 89% (n = 57/64) and 81.4% (n = 57/70), respectively. Both the PP and ITT eradication rates were superior in the LACB-14 group, compared with the LACB-7 group (PP: 90.6% vs. 87.5%; ITT: 81.4% vs. 80%, respectively), but these differences were not statistically significant (P = 0.689). Conclusions: Both the 7-day and 14-day first-line LACB therapies provided a high cure rate, were well tolerated, and were equally effective against H. pylori infection in Turkey.