Background; Self- learning module (SLM) is essential in assisting nurses to meet the challenges presented in today's health care environment. Aim; the study aimed to evaluate the effect of self -learning module on nurses' performance regarding care of patients with chest tube. Design; Quasi experimental design was used. Setting; the study was conducted at general chest department and chest intensive care unit at Benha University Hospital. Subjects; All available nurses (50) who were working in previous settings and agreed to participate in the study .Tools: two tools were used; (Tool I): nurses self-administered questionnaire for assessing nurses' knowledge regarding care of patient with chest tube and underwater seal drainage system (Tool II): nurses' practice observational checklist for assess level of nurse's practice regarding caring of patient with chest tube and underwater seal drainage system. Results; revealed that 46% were in the age category of 25≥ 30, 48% of nurses had diploma education level and 36% had experience of 5≥10year. Regarding total nurses' knowledge level 4% of them have satisfactory pre SLM intervention, however after one month post intervention 96% were having satisfactory but after 3months slight decline to 92% in level of knowledge. Regarding their total practices score only 6% of them have adequate level pre SLM intervention, while one month post intervention, 46% of them have adequate level but after 3 months slight decline to 34% adequate level. Conclusion: The majority of studied nurses had unsatisfactory knowledge and inadequate practices before SLM intervention, while they had satisfactory knowledge and adequate practices post SLM intervention. Also there will be a significant positive correlation between nurses' knowledge and practice post implementing SLM. Recommendations; Self -learning modules should be developed by nurse educators as a learning source material available to staff nurses in clinical settings for learning at their own time and pace, also building the flexibility and create awareness among staff nurses about significance of self-directed learning.