Objective:To identify and compare behaviors of children during vaccination, who were prepared or not for the procedure using an instructional therapeutic play.Methods:A quasi experimental study, with quantitative approach of 60 children aged 3 to 6 years. The child's reactions were recorded in a checklist. Data were analyzed using descriptive and inferential statistics and Fisher's test.Results:The main reactions in the experimental group were stay still (25;83%) and spontaneously collaborate (24;80%). In the control group, the main reactions were cries and cling to parents (15; 50%), flushing (11;36.67%) and moving the body/agitated (10;33.3%).Conclusion:The reactions of cooperation were more frequent in the experimental group, while low acceptance was observed only in the control group. Therapeutic play has proved an important tool in preparing for the vaccine.