Objective: to analyze satisfaction, self-confidence and performance of nursing students in realistic immunization simulation. Methods: quasi-experimental study, using the Immunization Checklist and Student Satisfaction and Self-confidence in Learning Scale, with 72 students, divided into Group 1 (38 seventh semester students who have not yet been in the field of practice in the Child Health discipline) and Group 2 (34 ninth semester students). Results: there was no difference between groups in terms of immunization performance (t-test: 1.701; p=0.096), as well as in terms of the degree of performance (Likelihood Ratio: 1.939; p=0.164). There was a significant difference when assessing satisfaction and self-confidence in learning (t-test: 2.346; p=0.023). Conclusion: the previous practice of immunization in the field of practice did not influence the performance of nursing students during the realistic simulation, but it did interfere with satisfaction and self-confidence in learning.