The final paper describes the specifics of fire protection at Combined Plant 4 at the Sisak Oil Refinery. Sisak Oil Refinery is a complex refinery intended for the processing of domestic and imported oil. It consists of several combined plants and a large storage area. Most of the refinery was built in the 1970s and has become obsolete and neglected, and therefore poses a potential environmental hazard, although there have been measures taken to changes this, especially in the past ten years. Due to the very nature of oil extraction and processing activities and the handling of oil and petroleum products, there is a high risk of fires and explosions that can have far-reaching consequences for the health and life of employees of the Sisak Oil Refinery, the surrounding population and the environment. For these reasons, it is very important that all fire and explosion protection measures are taken in a timely manner and that all employees strictly adhere to the rules of operation, but also to be able to act according to the elaborated plan and instructions in case of emergencies such as fires and explosions. Fire protection in the Republic of Croatia is defined by the Fire Protection Act, by-laws and autonomous sources of rights which legal persons are obliged to enact pursuant to laws and regulations. At the Sisak Oil Refinery, regulations related to fire protection are the Threat Assessment and the Fire Protection Plan. The threat assessment is the basic document used for the analysis of the facts and on the basis of which specific measures, including fire protection systems, preventive and organizational measures, are proposed by expert analysis. The fire protection plan is based on measures and regulations that prevent the risk of fire hazards and on the basis of which the work and organization of the fire department of the Sisak Oil Refinery are organized.