Objective: This study was conducted to determine the feelings and thoughts of nursing students in the roles of nurse and patient about the first intramuscular injection (IMI) to a person. Material and Methods: Pretest-posttest trial model was used in the study. The sample of the study consisted of 80 volunteers from the students who took the nursing fundamentals course. The sample group students performed the IMI application according to the scenario prepared by the researchers in the laboratory in which the students were in the roles of both nurse and patient under the supervision of instructors. The data of the study were collected before and after the procedure using a questionnaire form. Descriptive statistical analyses and paired sample t-test were used in the analysis of the data. Results: While in the patient role, students’ mean scores of feelings such as anxiety, irritation, nervousness, panicking, distress, scare, and embarrassment decreased after the IMI compared to pretest values (p<0.05), students’ mean scores of feelings such as being relieved, happiness, courage and calmness increased compared to pretest values (p<0.05). In nurse role, students’ mean scores of feelings such as irritation, distress, anxiety, and fear of complications decreased after the IMI compared to pretest values (p<0.05), while mean scores of feelings such as happiness, calmness, being relieved, courage, excitement and self-confidence increased (p<0.05). Conclusion: In both roles, the negative feelings and thoughts of the students before the IMI decreased after the application, and their positive feelings and thoughts increased. In line with the findings, it can be said that the study made significant contributions to the perspectives of the students as a professional member.