After the immunization procedure, it used to know as Post-Immunization Adverse Event (KIPI). This incident experienced by someone after receiving immunization such as redness in the injection area (phlebitis), irritable, fever or death. The drug commonly used for fever due to post immunization is paracetamol. Thus, the proper use of paracetamol is important to do so there is no error in the use of paracetamol for post immunization patients. The purpose of this study was forobserving the participant’s knowledge level and accuracy in using paracetamol for fever due to immunization procedure in Kasihan 1 Primary Health Center, Yogyakarta. This study wasused descriptive experimental methodfor data collection by using leaflets as a tool for counseling, questionnaire and patient's daily cards. The study population was all parents of patients who were received immunization procedure at Kasihan 1 Primary Health Center, Yogyakarta. In this study 30 respondents were involved as samples which were then divided into counseling group and non-counseling group. The data then were analyzed to determine the level of knowledge of respondents in using paracetamol which assessed by simple calculation formula. The accuracy of the use of paracetamol was analyzed using the percentage of questionnaire scoring results. The results obtained in this study show that the level of knowledge in using paracetamol fromcounseling groupwas80% which considered as good knowledge category, while respondent from non-counseling groupwas 71%which considered as moderate knowledge category. The result of accuracy in the use of paracetamol for fever due to post immunization was 100% which found in the counseling group, while the non-counseling group has less percentage that was only 78%. This study can conclude that the role of pharmacist to apply counseling is needed for improving the accuracy of the use of paracetamol according topost immunization patients.