Bacteria from the exit site of dialysis catheter can grow into microcolonies in biofilm. It has been hypothesized that rifampin-protamine combination may have an effect on the biofilm. In hemodialysis centre a combination of rifampin mixed with protamine is commonly used in some centre in order to prevent catheter related infections in hemodialysis patients. Therefore, a pharmaceutical assessment of the rifampin-protamine mixture is clearly mandatory. The aim of this study is to evaluate the stability and the sterility of the rifampin-protamine solution. Five milliliters of protamine (10 mg) was mixed with 10 mL of Rifampin (600 mg). The solution was kept at -20 degrees C temperature for two weeks and subsequently at 4 degrees C for two additional weeks. Stability and sterility were evaluated the first day and two weeks, three weeks and four weeks after the preparation. Concentration of rifampin in the solution was assessed by HPLC. Protamine concentration was evaluated by the effect of the solution on the heparin activity of a heparinized plasma. The solution was cultured on broth media and mannitol agar plate. Areas under curve of rifampin were similar between the four different evaluations. The effect of the solution on the heparin activity was comparable at the four different evaluations. Our results demonstrate the stability and the compatibility of the solution. However, there was biological interference between broth media and the solution. It was, therefore, impossible to make any conclusion after broth culture. Culture on mannitol agar plate did not show any microbiological growth. Based on this finding, we recommend preparing the rifampin-protamine combination in individual conditioning at the time of the utilization.