【Abstract】 Objective To evaluate the efficacy of OM85（bacterial lysate） on acute attacksrelated indicators and immune function in patients with stable bronchiectasis.Methods 62 patients with bronchiectasis were randomly divided into treatment group (N=34) and control group (N=28). The control group received standard optimized care and the treatment group received treatment with OM85 oral (dten consecutive days per month, for 3 months). The serum levels of C3, C4, and Ig were observed before and after treatment. The number and duration of acute exacerbations, and time for the use of antibiotics were compared between the two groups after treatment.Results The indexes in the treatment group were lower than those in the control group (P＜005). There were no significant changes in the various indicators before and after treatment in the control group (P＞005). In the treatment group, complement C3, C4, serum immune proteins (IgM, IgG and IgA) were significantly increased and IgE levels were significantly decreased before and after treatment (P＜005). The levels of C3, C4,IgM, IgG and IgA in the treatment group were significantly higher than those in the control group, and the IgE level was lower than that in the control group (P＜005).Conclusion The application of OM85 in the stable bronchiectasis can improve the patient's immune function, enhance the body's antiinfective ability, reduce the number of acute attacks, the duration of acute attacks and the use of antibiotics.