Purpose: The purpose of the study is to offer necessary data to develop nursing interventions to reduce intravenous injection pain and uneasiness among hospitalized children. Methods: A total of 200 patients aged 1-72 months were selected. Pain during intravenous cannulation was assessed using the Procedural Behavior Checklist (PBCL) and the Faces Pain Rating Scale (FPRS). Data were analyzed by t-test and ANOVA using the SPSS/WIN 12.0. Results: Younger patients showed higher pain response than older patients (F=33.87, p<.001). Children with respiratory diseases showed higher responses in FPRS and PBCL than children without respiratory disease (F=4.17, p=.017; F=25.31, p<.001, respectively). Children of preschool age showed higher pain response during IV cannulation than the comparison group (t=2.04, p=.045). Children who had previous experiences with hospitalization and injections showed higher response to pain than those without these experiences (t=2.05, p=.045). In regards to FPRS, patients who were recannulated showed more painful restarts compared with patients injected just once (t=-3.60, p<.001). In regards to PBCL, infants and toddlers (t=-4.88, p<.001) and preschoolers (t=-3.86, p<.001) showed high pain scores during recannulation. Conclusion: A sick child's response to pain may be worse as they feel more pain over time. These characteristics should be considered for development of nursing interventions