This thesis describes the legal position of foreign citizens before the courts of the Republic of Croatia with an emphasis on security for costs. A foreign citizen is any person who is not a Croatian citizen. Foreign citizens are granted the right to act before the Courts of Croatia in the role of prosecutor, defendant and intervener. Also, they are recognized for party and litigation abilities and procedural legitimation. Security for costs, the institute of procedural cost insurance, is regulated by the Private International Law Act and can only be required in disputes with an international element. This is the value that the plaintiff is obliged to deposit with the court at the request of the defendant, and at that same value the defendant acquires a legal lien in order to later be able to collect litigation costs that the plaintiff would be obliged to reimburse him at the court's decision. The thesis defines the role of security for costs as a procedural burden for the plaintiff, the method of payment that is most often in money, its amount, which is determined according to the circumstances of the case, the conditions under which it can be sought and other details related to it. Also, the problem of foreigners in terms of ignorance of the official language of the court and the role of interpreters in court proceedings tasked with translating proceedings is described. Finally, it is mentioned the possibility of foreigners acting as representatives of the party before the courts of Croatia.