Aims: Pains caused by the invasive actions such as intramuscular injection lead to the physical and mental tensions in the children. Therefore, such pains should be given relief. One of the main priorities in the nursing is to notice methods that reduce pains due to the invasive actions in the children. The aim of this study was to investigate the effects of injection displayed on a doll on the pain intensity due to the intramuscular injection in the preschool children. Materials & Methods:In the randomized controlled clinical trial, 62 kids aged between 4 and 6 years with pharyngitis were studied in the clinic of the health network of Khalil-abad Township in 2015. The intramuscular injection of penicillin 6.3.3 was administrated for the kids. The subjects, selected by simple lottery, were divided into two groups including experimental and control groups (n=31 per group). Data was collected using a demographic characteristic collecting form and Oucher standard pain assessment tool. In experimental group, the kid watching, one intramuscular injection was displayed on a doll by a nurse; then, the kid underwent an intramuscular injection. In control group, the routine injection method was done. Data was analyzed by SPSS 19 software using Mann-Whitney, independent T, and Chisquare tests. Findings: Mean pain intensity after injection in experimental group (3.22±0.90) was significantly lower than control group (4.19±0.83; p<0.001). Conclusion: The injection displayed on a doll before the intramuscular injection might lead to pain reduction in the preschool kids.