The aim of this study is to determine the effect of being in a favour of a team of polices who are on duty in sports competition.Sample of the study is 609 policemen from Çevik Kuvvet Şube Müdürlüğü in Ankara, İstanbul, İzmir, Trabzon and Antalya. A questionnaire including 13 questions and X2 (Chi-scuare-Ki-Kare) test of SPSS Statistical Evaluation Software version 11.0 is applied in the study. For statistical acceptance level of 0.05 (p) is accepted.As a result of the study it is observed that 58.0% of policemen are actively interested in sports, 98.0% evaluate supporters as aggressive and thinks that 54.4% of supporters go to matches aiming to de-charge. 87.3% of policemen think that they start the duty very early and high portion of them do not want to take an assignment onmatches. 65.6 % of them think that press, sports club management, referees, competitor’s supporters, sportsmen mistakes, technical men and cheerleader are reasons for supporters’ aggressiveness. 91.3% of them thinks that, supporters whose aggressiveness are determined before should be forbidden to enter the matches. Policemen’stendencies to support a team and degree of interest in sport are effective in toleration to their supported team’s lost in a match (p<0.05). There is a significant relationship (p<0.05) between being in a favour of a team of policemen and their willingness to take assignments in matches, tolerating supporters in national matches and using force in case of supporters violation to public commodity. It is found that there is not a significant relationship (p>0.05)between taking an assignment in their favourite team’ matches and their privileged behaviour to supporters and their ideas about setting up a different department like sports police.According to findings, it can be said that policemen leave behind of their supporter identities in a professional mood when the are on duty, they behave more tolerable in national matches by the effect of their national feelings, in violent behaviours of supporters they do not keep away from use violence in order to obtain public order and security. It can be said that their high portion of the aim of being part in sport is entertainment, recreation and health.