Objective:To study the effect of phage lysin on the growth of lysogens.Methods:Sputum specimens processed by modified Petroff’s method were respectively treated with phagebiotics in combination with lysin and lysin alone.The specimens were incubated at 37 ℃ for 4 days.At the end of day 1,2,3 and day 4,the specimens were streaked on blood agar plates and incubated at37 ℃ for 18-24 hours.The growth of normal flora observed after day 1 was considered as lysogens.Results:Sputum specimens treated with phagebiotics-lysin showed the growth of lysogens.When specimens treated with lysin alone,lysogen formation was avoided and normal flora was controlled.Conclusions:Lysin may have no effect on the growth of lysogens. Objective: To study the effect of phage lysin on the growth of lysogens. Methods: Sputum specimens processed were modified by Petroff’s method were respectively treated with phagebiotics in combination with lysin and lysin alone. The specimens were incubated at 37 ° C for 4 days. At the the end of day 1,2,3 and day 4, the specimens were streaked on blood agar plates and incubated at 37 ° C for 18-24 hours. The growth of normal flora observed after lys 1 was considered as lysogens. Results: Sputum specimens treated with phagebiotics-lysin showed the growth of lysogens. When specimens treated with lysin alone, lysogen formation was avoided and normal flora was controlled. Conclusions: Lysin may have no effect on the growth of lysogens.