Objective The present study was aimed to compare the effect of the trained and untrained family presence on their anxiety during invasive procedures in an emergency department. Methods In this randomized controlled clinical trial, 90 patients who were candidates for receiving invasive nursing procedures were selected in an emergency department based on the inclusion criteria, and then were equally assigned into 3 groups by the random minimization method: A ("presence of the trained family member group "), B ("presence of the untrained family member group "), and C ("absence and untrained family member group"). The anxiety level was measured before and after implementation of the procedure using the Spielberger State-Trait Anxiety Inventory (STAI). The data were analyzed by SPSS software using the Kolmogorov-Smirnov test, Chi-Square test, Kruskal Wallis Independent-Samples test, Paired Samples T-test, and ANOVA at the significance level of 0.05. Results The three groups were similar in terms of demographic variables. In all three groups, the SATI score significantly decreased after intervention phase (p = 0.001). The mean changes of the SATI score were not statistically different between the groups. However, The STAI score decreased significantly after intervention in the group B compared to the group A (p = 0.011) and C (p = 0.042). However, there was no significant difference between the SATI score in the group A and C (p = 0.867). Conclusion The results of the study revealed that, the “presence of the untrained" family members caused them to experience significantly less anxiety than the other two groups. However, changes in the anxiety score were not significant between the groups.