The aim of the article is to verify the hypothesis that the institution of reinstatement to police service is a very important element of administrative and legal protection of all police officers in Poland. The service relationship, within the framework of which a police officer performs the activities entrusted to him by the state, is an administrative and legal relationship, the characteristic feature of which is the establishment by the legislator of a catalogue of reasons justifying the dismissal of a police officer from service. Reinstatement to service, on the other hand, is an institution that allows a dismissed police officer, in cases specified by the legislator, to return to service in the Police. This publication analyzes reinstatement to service and activities related to it, in particular the police officer's notification of readiness to take up service, determining the police officer's fitness to serve in the Police and issuing a personal order to appoint a police officer to the position. The work also determines the impact of reinstatement to service on the content of the police officer's service relationship, which is of significant importance from the point of view of the officer's rights. The analysis conducted allowed for the confirmation of the research hypothesis stated at the beginning. Reinstatement to police service is a very important manifestation of administrative and legal protection of all police officers in Poland. This institution constitutes an expression of their protection against the negative consequences resulting from dismissal from police service.