Objective: Tunneled cuffed dual-lumen catheters (TCCs) are commonly used for vascular access in hemodialysis (HD) patients. Catheter-related bloodstream infection (CRBSI) is the major problem leading to morbidity and mortality. We investigated whether 26% NaCl solution has any favorable effect on the infections and thrombosis caused by HD catheters. Methods: TCCs were locked with either 26% NaCl and heparin or standard heparin. The primer end point of the study was the CRBSI or thrombosis of the TCC. We compared the antimicrobial activity of the NaCl solutions (6.5%, 13%, 26%) with 0.9% NaCl solution by time-kill kinetic assay. All tests were performed in triplicate by incubation of test fluids with Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. Results: The mean catheter survival was significantly higher in the 26% NaCl and heparin group (129.5 +/- 50.1 catheter days to 103.3 +/- 59.8, p = 0.008). CRBSI rates (10-15.4%) did not differ significantly between the two groups (p = 0.54). The hypertonic 13% NaCl solution had bactericidal effects on E. coli and P. aeruginosa, but had bacteriostatic effect on S. aureus and S. epidermidis. Conclusion: In this study we demonstrated that the 13% NaCl solution and more hypertonic NaCl solutions revealed potent in vitro antimicrobial properties against all checked Gram-negative microorganisms.