Hospitalization and invasive procedures impose a significant anxiety in the young children. Children's anxiety of the invasive procedures represented in behavioral and physiological changes , which are upsetting them and their parents. In addition, it makes it more difficult to complete the needed procedure. One of the suggested methods to prepare children for invasive nursing procedures is to familiarize children with invasive procedures through therapeutic play. This study aimed to determine the effect of therapeutic play on the anxiety level as a preparation technique of children undergoing invasive nursing procedures. The study sample comprised 100 children of age 2-7 years, undergoing invasive nursing procedures. First admitted to Pediatric Department, Hematology/Oncology Unit at Tanta University Hospitals was included in the study. They were randomized into two equal groups: study group received therapeutic play before the invasive procedure and control group received routine hospital care. Two tools were used to collect the necessary data: the questionnaire sheet and the observation check list sheet. The main results yielded by the study proved that, significantly lower in anxiety level and physiological reactions to invasive nursing procedures in children underwent therapeutic play.