Background: Simulation provides students with the opportunity to improve their intended learning outcomes such as clinical performance, knowledge acquisition, clinical reasoning and student satisfaction. The aim of this study was to investigate the effect of simulation based learning on improving cognitive achievement of nursing students during care of patients with bronchial asthma. A quasi-experimental design was used in this study on 100 nursing students at Medical surgical Nursing simulations Lab in Faculty of Nursing, Beni-Suef University. Four tools were used: cognitive achievement tool, Students' practice observational checklist, Simulation Effectiveness Tool and perceived competence scales. Results showed that there was a statistical significant difference between the nursing students' level of knowledge before and after application of simulation (p<0.001**) and showed that simulation based learning group showed the highest scores in practice compared to groups using traditional methods alone. Conclusion: the level of nursing students' knowledge and practice were generally improved after application of simulation based learning strategy about bronchial asthma. The simulation based learning has a significant influence in improving the cognitive abilities of nursing students in practicing nursing care in the case of patients with bronchial asthma, compared to face-to-face lectures. Recommendations: Nursing education programs should adopt and support the introduction of simulation in undergraduate education and curriculum development.